[GRASS-git] [OSGeo/grass] 20a1bc: CI: Update Flake8 (#1932)

[Vaclav Petras]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 20a1bcc262c81caf76b60aaf23df5bf30e0bb0e9
      https://github.com/OSGeo/grass/commit/20a1bcc262c81caf76b60aaf23df5bf30e0bb0e9
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2021-10-07 (Thu, 07 Oct 2021)

  Changed paths:
    M .github/workflows/flake8.yml

  Log Message:
  -----------
  CI: Update Flake8 (#1932)

* Update Flake8 to version 3.9.2.
* Update Python used for the job to 3.10.
* Remove unused name from the matrix.
* Fix version of Python. It is a string, not float.