[GRASS-git] [OSGeo/grass] 87fdb4: Increase minimum Python version to 3.7 (#2241)

[Vaclav Petras]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 87fdb472fb2eb1ed98584bae19da524133f4c3f5
      https://github.com/OSGeo/grass/commit/87fdb472fb2eb1ed98584bae19da524133f4c3f5
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2022-03-02 (Wed, 02 Mar 2022)

  Changed paths:
    R .github/workflows/build_ubuntu-18.04.sh
    M .github/workflows/centos.yml
    M .github/workflows/pylint.yml
    M .github/workflows/ubuntu.yml
    M REQUIREMENTS.html
    M pyproject.toml

  Log Message:
  -----------
  Increase minimum Python version to 3.7 (#2241)

This does not make the code incompatible with Python 3.6, but does not check for Python 3.6 compatibility anymore which makes it possible to include Python >=3.7 only code.

To be clear, the minimum required Python version is now Python 3.7, so using features which are only in 3.7 and above is perfectly fine.

This removes Ubuntu 18.04 test from the CI because 18.04 uses Python 3.6 and therefore 18.04 in its default configuration is now no longer supported.