Starting with wheel 0.32.0 (2018-09-29), the `license_file` option is deprecated.

* https://wheel.readthedocs.io/en/stable/news.html

The wheel will continue to include `LICENSE`, it is now included automatically:

* https://wheel.readthedocs.io/en/stable/user_guide.html#including-license-files-in-the-generated-wheel-file

And `LICENSE` is still included in sdists thanks to setuptools-scm:

* pytest-dev#6348 (comment)

…rder

tests: add test_plugin_loading_order

…file-metadata

Remove deprecated license_file from setup.cfg

This is implemented by the underlying stream already, which additionally
checks if the stream is not closed, and calls `write` per line.

Ref/via: pytest-dev#6558 (comment)

Might be slow on CI.

Ref: https://github.com/pytest-dev/pytest/pull/6570/checks?check_run_id=408752475#step:6:109

While it might not help with the following, it certainly might happen as
well.

```
+ curl -S -L --connect-timeout 5 --retry 6 -s https://codecov.io/bash -o codecov-upload.sh
curl: (16) Error in the HTTP2 framing layer
```

…nnrefused

ci: codecov: use `--retry-connrefused` with curl

…ollect_only_live_logging

tests: test_collection_collect_only_live_logging: allow for 1+s

Via pytest-dev#6574.

tests: add test_via_exec

…ines

Fix `EncodedFile.writelines`

mypy: show_error_codes=True

typing: Testdir.__init__