Add path web app run

[SamirPS]

What do these changes do?

I modify the web.py file and add Union[str,pathlib.Path] for path

Are there changes in behavior for the user?

For the option of path, we can have str or pathlib.path

Related issue number

#6839

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> for example (588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the pr
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."

[Dreamsorcerer]

Need to see a test covering this. Could probably just remove str() from these 2:
https://github.com/aio-libs/aiohttp/blob/master/tests/test_run_app.py#L521
https://github.com/aio-libs/aiohttp/blob/master/tests/test_run_app.py#L535

[SamirPS]

Need to see a test covering this. Could probably just remove str() from these 2: https://github.com/aio-libs/aiohttp/blob/master/tests/test_run_app.py#L521 https://github.com/aio-libs/aiohttp/blob/master/tests/test_run_app.py#L535

Okay i remove str() for this two test and all test in this file passed

[Dreamsorcerer]

Also, test failing. Looks like there's another place that needs a Union[] annotation.

[SamirPS]

@Dreamsorcerer For me all test passed or skipped because i working on ubuntu (WSL)

[lgtm-com]

This pull request introduces 1 alert when merging 6391e9e into 934db9a - view on LGTM.com

new alerts:

• 1 for Module is imported with 'import' and 'import from'

[Dreamsorcerer]

We run a lot of tests in CI, so check the output. You should be able to reproduce the mypy errors on your machine, by simply running mypy.