https://github.com/aio-libs/aiohttp/pull/7178#issuecomment-1406829939

- Drop some workarounds related to the test suite that are no longer necessary.
- Patch test_circular_imports.py to respect our custom PYTHONPATH.
- Update the PYTHONPATH location according to the changes in setuptools 62.1.0.

- Without python-setuptools the package fails to build with --nocheck.
- PYTHONDONTWRITEBYTECODE seems to be no longer required when using PEP 517,
  the bytecode is the same regardless of whether check() is run or not.

The official rebuilderd instance rebuilds without running check(), so make sure
the test suite does not change the generated bytecode.

- Add new dependencies
- Remove upstreamed patches
- Switch from http-parser to llhttp
- Work around some weirdness with the test suite