[GRASS-git] [OSGeo/grass] 30bbdd: CI: Use a specific Flake8 version (#626)

[Vaclav Petras]

  Branch: refs/heads/master
  Home:   https://github.com/OSGeo/grass
  Commit: 30bbdd136ae4d8977ba980d89118d57b7cd35d6f
      https://github.com/OSGeo/grass/commit/30bbdd136ae4d8977ba980d89118d57b7cd35d6f
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2020-05-12 (Tue, 12 May 2020)

  Changed paths:
    M .github/workflows/flake8.yml
    M lib/python/pygrass/tests/benchmark.py

  Log Message:
  -----------
  CI: Use a specific Flake8 version (#626)

This adds a version specification to the Flake8 install in CI,
namely 3.8.0, the latest release.

It fixes string formatting issue (F523) in one file.
This fixes #619.

This also does some polish in the CI config file to tell that this is Python
and it removes the now unused continue-on-error lines.