text: Title: tox-docker configuration parsing broken since tox 4.0.13
  Body: ## Issue
  
  tox-docker plugin configuration parsing of `ports`  is broken since tox 4.0.13.
  
  `ports` configuration option is documented as:
  
  > A multi-line list of port mapping specifications, as `HOST_PORT:CONTAINER_PORT/PROTO`, ...
  
  With 4.0.12, the host port is properly set on the started container and forwarded to the container port.
  
  But with tox 4.0.13, host port of the started container is random.
  Given the short changelog for that release, I suspect it to be caused by https://github.com/tox-dev/tox/pull/2744
  Same issue occurs with 4.0.15, 4.0.19, and 4.2.2.
  
  ## Environment
  
  Provide at least:
  
  - OS: Ubuntu 22.10
  - `pip list` of the host Python where `tox` is installed:
  
  ```console
  # poetry run pip list
  Package            Version     Editable project location
  ------------------ ----------- -------------------------------------------------------------------------------------
  attrs              21.4.0
  black              22.3.0
  boto3              1.23.6
  botocore           1.26.6
  cachetools         5.2.0
  certifi            2022.5.18.1
  cfgv               3.3.1
  chardet            5.1.0
  charset-normalizer 2.0.12
  click              8.1.3
  colorama           0.4.6
  distlib            0.3.6
  docker             5.0.3
  filelock           3.9.0
  flake8             4.0.1
  freezegun          1.2.1
  identify           2.5.1
  idna               3.3
  iniconfig          1.1.1
  jmespath           1.0.0
  mccabe             0.6.1
  mock               4.0.3
  mypy-extensions    0.4.3
  nodeenv            1.6.0
  packaging          22.0
  pathspec           0.9.0
  pip                22.3.1
  platformdirs       2.6.2
  pluggy             1.0.0
  pre-commit         2.19.0
  py                 1.11.0
  pycodestyle        2.8.0
  pyflakes           2.4.0
  pyparsing          3.0.9
  pyproject_api      1.4.0
  pytest             6.2.5
  pytest-mock        3.7.0
  python-dateutil    2.8.2
  PyYAML             6.0
  requests           2.27.1
  s3transfer         0.5.2
  setuptools         65.6.3
  six                1.16.0
  toml               0.10.2
  tomli              2.0.1
  tox                4.2.2
  tox-docker         4.0.0a2
  urllib3            1.26.9
  virtualenv         20.17.1
  websocket-client   1.3.2
  wheel              0.38.4
  ```
  
  ## Output of running tox
  
  Provide the output of `tox -rvv`:
  
  ```console
  tox -rvv
  /home/patrick/workspaces/myproject/.venv/lib/python3.10/site-packages/requests/__init__.py:102: RequestsDependencyWarning: urllib3 (1.26.9) or chardet (5.1.0)/charset_normalizer (2.0.12) doesn't match a supported version!
    warnings.warn("urllib3 ({}) or chardet ({})/charset_normalizer ({}) doesn't match a supported "
  py39: 298 W remove tox env folder /home/patrick/workspaces/myproject/.tox/py39 [tox/tox_env/api.py:321]
  py39: 308 I find interpreter for spec PythonSpec(major=3, minor=9) [virtualenv/discovery/builtin.py:56]
  py39: 308 D discover exe for PythonInfo(spec=CPython3.10.6.final.0-64, exe=/home/patrick/workspaces/myproject/.venv/bin/python, platform=linux, version='3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0]', encoding_fs_io=utf-8-utf-8) in /usr [virtualenv/discovery/py_info.py:437]
  py39: 308 D filesystem is case-sensitive [virtualenv/info.py:24]
  py39: 310 D got python info of /usr/bin/python3.10 from /home/patrick/.local/share/virtualenv/py_info/1/8a94588eda9d64d9e9a351ab8144e55b1fabf5113b54e67dd26a8c27df0381b3.json [virtualenv/app_data/via_disk_folder.py:129]
  py39: 310 I proposed PythonInfo(spec=CPython3.10.6.final.0-64, system=/usr/bin/python3.10, exe=/home/patrick/workspaces/myproject/.venv/bin/python, platform=linux, version='3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0]', encoding_fs_io=utf-8-utf-8) [virtualenv/discovery/builtin.py:63]
  py39: 310 D discover PATH[0]=/home/patrick/workspaces/myproject/.venv/bin [virtualenv/discovery/builtin.py:108]
  py39: 311 D got python info of /home/patrick/workspaces/myproject/.venv/bin/python3 from /home/patrick/.local/share/virtualenv/py_info/1/f40e8b45bd8922e09aa5a9356903620c1975d00691ae8ec9747c29426f7f443d.json [virtualenv/app_data/via_disk_folder.py:129]
  py39: 311 D discover exe from cache /usr - exact False: PythonInfo({'architecture': 64, 'base_exec_prefix': '/usr', 'base_prefix': '/usr', 'distutils_install': {}, 'exec_prefix': '/usr', 'executable': '/home/patrick/workspaces/myproject/.venv/bin/python', 'file_system_encoding': 'utf-8', 'has_venv': True, 'implementation': 'CPython', 'max_size': 9223372036854775807, 'original_executable': '/usr/bin/python3.10', 'os': 'posix', 'path': ['/home/patrick/.local/pipx/venvs/tox/lib/python3.10/site-packages/virtualenv/discovery', '/usr/lib/python310.zip', '/usr/lib/python3.10', '/usr/lib/python3.10/lib-dynload', '/home/patrick/.local/lib/python3.10/site-packages', '/usr/local/lib/python3.10/dist-packages', '/usr/lib/python3/dist-packages'], 'platform': 'linux', 'prefix': '/usr', 'real_prefix': None, 'stdout_encoding': 'utf-8', 'sysconfig': {'makefile_filename': '/usr/lib/python3.10/config-3.10-x86_64-linux-gnu/Makefile'}, 'sysconfig_paths': {'data': '{base}', 'include': '{installed_base}/include/python{py_version_short}{abiflags}', 'platlib': '{platbase}/{platlibdir}/python{py_version_short}/site-packages', 'platstdlib': '{platbase}/{platlibdir}/python{py_version_short}', 'purelib': '{base}/lib/python{py_version_short}/site-packages', 'scripts': '{base}/bin', 'stdlib': '{installed_base}/{platlibdir}/python{py_version_short}'}, 'sysconfig_scheme': 'posix_prefix', 'sysconfig_vars': {'PYTHONFRAMEWORK': '', 'abiflags': '', 'base': '/usr', 'installed_base': '/usr', 'platbase': '/usr', 'platlibdir': 'lib', 'py_version_short': '3.10'}, 'system_executable': '/usr/bin/python3.10', 'system_stdlib': '/usr/lib/python3.10', 'system_stdlib_platform': '/usr/lib/python3.10', 'version': '3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0]', 'version_info': VersionInfo(major=3, minor=10, micro=6, releaselevel='final', serial=0), 'version_nodot': '310'}) [virtualenv/discovery/py_info.py:435]
  py39: 311 D discover exe from cache /usr - exact False: PythonInfo({'architecture': 64, 'base_exec_prefix': '/usr', 'base_prefix': '/usr', 'distutils_install': {}, 'exec_prefix': '/usr', 'executable': '/home/patrick/workspaces/myproject/.venv/bin/python3', 'file_system_encoding': 'utf-8', 'has_venv': True, 'implementation': 'CPython', 'max_size': 9223372036854775807, 'original_executable': '/usr/bin/python3.10', 'os': 'posix', 'path': ['/home/patrick/.local/pipx/venvs/tox/lib/python3.10/site-packages/virtualenv/discovery', '/usr/lib/python310.zip', '/usr/lib/python3.10', '/usr/lib/python3.10/lib-dynload', '/home/patrick/.local/lib/python3.10/site-packages', '/usr/local/lib/python3.10/dist-packages', '/usr/lib/python3/dist-packages'], 'platform': 'linux', 'prefix': '/usr', 'real_prefix': None, 'stdout_encoding': 'utf-8', 'sysconfig': {'makefile_filename': '/usr/lib/python3.10/config-3.10-x86_64-linux-gnu/Makefile'}, 'sysconfig_paths': {'data': '{base}', 'include': '{installed_base}/include/python{py_version_short}{abiflags}', 'platlib': '{platbase}/{platlibdir}/python{py_version_short}/site-packages', 'platstdlib': '{platbase}/{platlibdir}/python{py_version_short}', 'purelib': '{base}/lib/python{py_version_short}/site-packages', 'scripts': '{base}/bin', 'stdlib': '{installed_base}/{platlibdir}/python{py_version_short}'}, 'sysconfig_scheme': 'posix_prefix', 'sysconfig_vars': {'PYTHONFRAMEWORK': '', 'abiflags': '', 'base': '/usr', 'installed_base': '/usr', 'platbase': '/usr', 'platlibdir': 'lib', 'py_version_short': '3.10'}, 'system_executable': '/usr/bin/python3.10', 'system_stdlib': '/usr/lib/python3.10', 'system_stdlib_platform': '/usr/lib/python3.10', 'version': '3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0]', 'version_info': VersionInfo(major=3, minor=10, micro=6, releaselevel='final', serial=0), 'version_nodot': '310'}) [virtualenv/discovery/py_info.py:435]
  
  ```
  Way too verbose to post completely.
  
  ## Minimal example
  
  If possible, provide a minimal reproducer for the issue:
  
  With this tox.ini:
  ```ini
  [docker:dynamoDB]
  image = amazon/dynamodb-local:latest
  ports = 8000:8000/tcp
  
  [testenv]
  docker =
      dynamoDB
  commands =
      pytest tests/ {posargs}
  ```
  
  With tox 4.0.12:
  ```console
  # docker ps
  CONTAINER ID   IMAGE                          COMMAND                  CREATED         STATUS        PORTS                                       NAMES
  d3c1a6403b59   amazon/dynamodb-local:latest   "java -jar DynamoDBL…"   2 seconds ago   Up 1 second   0.0.0.0:8000->8000/tcp, :::8000->8000/tcp   dynamoDB-tox-364494
  ```
  
  With tox 4.0.13 and higher:
  ```console
  # docker ps
  CONTAINER ID   IMAGE                          COMMAND                  CREATED         STATUS         PORTS                                         NAMES
  4de548f795c3   amazon/dynamodb-local:latest   "java -jar DynamoDBL…"   2 seconds ago   Up 2 seconds   0.0.0.0:32790->8000/tcp, :::32790->8000/tcp   dynamoDB-tox-363635
  ```