Project restructurisation 2

[stankudrow]

Based on [cancelled] pull request 137. Changes:

1. Pythons: Python 3.6 removed, PyPy-3.8 over PyPy3.7;
2. Documentation: Sphinx has not been added yet -> docs need more time;
3. GitHub Actions workflow: the separate coverage job added, actions versions updated;
4. Coverage: 100% reached, the coverage under 90% is considered failure;
5. Functionality:

• asyncify (former wrap) function is more similar to asyncio.to_thread (Py3.9);
• a new isasync function added to check if the function parametre is already an "asynchronous" object.

This PR may address/solve the following issues:

• https://github.com/Tinche/aiofiles/issues/136 - asyncio_mode=strict in pytest.ini;
• https://github.com/Tinche/aiofiles/issues/132 - pyproject.toml enriched, republishing to PyPI should reveal the situation;
• https://github.com/Tinche/aiofiles/issues/129 - now get_running_loop() is used;

Backward compatibility fails for those having used wrap function, therefore, the next version may be 1.0.0, not 0.9.0.

[stankudrow]

Concerning isasync function -> may solve this issue https://github.com/Tinche/aiofiles/issues/92.

[stankudrow]

You might have meant CalVer (https://calver.org/calendar_versioning.html) - what is the reason for switching from SemVer to CalVer?

[stankudrow]

@Tinche , requested changes made, please consider reviewing.

[Tinche]

@stankudrow Sorry, had some time off and now I'm preparing a conference talk, will do ASAP.

You asked about why calver, here's a handy link: https://hynek.me/articles/semver-will-not-save-you/

[stankudrow]

No problem, thank you for the link.

[stankudrow]

@Tinche , maybe any other changes to add?

[Tinche]

@stankudrow Hello, I have some cycles to dedicate to this now ;)

I think you asked me whether the talk will be online, PyCon IT staff assures me that it will at some point.

[shan-guo]

这是来自QQ邮箱的假期自动回复邮件。您好，我最近正在休假中，无法亲自回复您的邮件。我将在假期结束后，尽快给您回复。

[shan-guo]

这是来自QQ邮箱的假期自动回复邮件。您好，我最近正在休假中，无法亲自回复您的邮件。我将在假期结束后，尽快给您回复。