text: Title: Bug: `exceptiongroup` backport is missing on Python 3.10
  Body: ### Description
  
  Code expects `exceptiongroup` backport to be installed in https://github.com/litestar-org/litestar/blob/6e4e530445eadbc1fd2f65bebca3bc68cf12f29a/litestar/utils/helpers.py#L101
  
  However, it's only declared for _dev_ dependencies in https://github.com/litestar-org/litestar/blob/6e4e530445eadbc1fd2f65bebca3bc68cf12f29a/pyproject.toml#L109 so after `litestar` install it won't be found and one has to manually require it now.
  
  Running Python 3.10.
  
  ### Logs
  
  Full stacktrace (failure on launch):
  
  ```
  
  Traceback (most recent call last):
    File "/home/api/.local/lib/python3.10/site-packages/litestar/utils/helpers.py", line 99, in get_exception_group
      return cast("type[BaseException]", ExceptionGroup)  # type:ignore[name-defined]
  NameError: name 'ExceptionGroup' is not defined. Did you mean: '_ExceptionGroup'?
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/usr/local/lib/python3.10/runpy.py", line 196, in _run_module_as_main
      return _run_code(code, main_globals, None,
    File "/usr/local/lib/python3.10/runpy.py", line 86, in _run_code
      exec(code, run_globals)
    File "/myproject/api/myproject/cloud_management/new_app.py", line 4, in <module>
      from litestar import Litestar
    File "/home/api/.local/lib/python3.10/site-packages/litestar/__init__.py", line 1, in <module>
      from litestar.app import Litestar
    File "/home/api/.local/lib/python3.10/site-packages/litestar/app.py", line 20, in <module>
      from litestar._openapi.plugin import OpenAPIPlugin
    File "/home/api/.local/lib/python3.10/site-packages/litestar/_openapi/plugin.py", line 10, in <module>
      from litestar.routes import HTTPRoute
    File "/home/api/.local/lib/python3.10/site-packages/litestar/routes/__init__.py", line 1, in <module>
      from .asgi import ASGIRoute
    File "/home/api/.local/lib/python3.10/site-packages/litestar/routes/asgi.py", line 7, in <module>
      from litestar.routes.base import BaseRoute
    File "/home/api/.local/lib/python3.10/site-packages/litestar/routes/base.py", line 13, in <module>
      from litestar._kwargs import KwargsModel
    File "/home/api/.local/lib/python3.10/site-packages/litestar/_kwargs/__init__.py", line 1, in <module>
      from .kwargs_model import KwargsModel
    File "/home/api/.local/lib/python3.10/site-packages/litestar/_kwargs/kwargs_model.py", line 49, in <module>
      _ExceptionGroup = get_exception_group()
    File "/home/api/.local/lib/python3.10/site-packages/litestar/utils/helpers.py", line 101, in get_exception_group
      from exceptiongroup import ExceptionGroup as _ExceptionGroup  # pyright: ignore
  ModuleNotFoundError: No module named 'exceptiongroup'
  ```
  
  ### Litestar Version
  
  2.5.1
  
  ### Platform
  
  - [X] Linux
  - [ ] Mac
  - [ ] Windows
  - [ ] Other (Please specify in the description above)