text: Title: Support Path type for repo argument
  Body: ## 🚀 Feature
  
  Add support for Path type to the `repo` attribute of the `Run` class.
  <!-- A clear and concise description of the feature proposal -->
  
  ### Motivation
  
  Currently, the `Run.repo` attribute supports only the str type. The Path type from pathlib is very convenient for dealing with paths, and it would be great to use it in a code to specify the repo of Aim run as well. Passing a Path type to `Run.repo` will keep the user's script clean and precise.
  <!-- Please outline the motivation for the proposal. Is your feature request related to a problem? e.g., I'm always frustrated when [...]. If this is related to another GitHub issue, please link here too -->
  
  ### Pitch
  
  A user should be able to pass a Path type to `Run.repo` argument.
  Say we have the following simple script:
  ```
  from pathlib import Path
  from aim import Run
  
  log_dir = Path("path/to/my/log/dir")
  ```
  The current way of passing the repo path is:
  ```
  run = Run(repo=str(log_dir))
  ```
  Having such an API would make the code clean
  ```
  run = Run(repo=log_dir)
  ```
  <!-- A clear and concise description of what you want to happen. -->
  