[GRASS-git] [OSGeo/grass] 3c6d23: CI: drop outdated CentOS 7 compilation (#3141)

[Markus Neteler]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: 3c6d23d9d7d0ae27ec61ae32d66bc759be54171f
      https://github.com/OSGeo/grass/commit/3c6d23d9d7d0ae27ec61ae32d66bc759be54171f
  Author: Markus Neteler <neteler at osgeo.org>
  Date:   2023-09-07 (Thu, 07 Sep 2023)

  Changed paths:
    R .github/workflows/build_centos.sh
    R .github/workflows/centos.yml
    R .github/workflows/yum.txt
    M README.md

  Log Message:
  -----------
  CI: drop outdated CentOS 7 compilation (#3141)

Remove of CentOS 7 compilation as no longer compatible with new GHA checkout v4 (see #3138 - Background: default runtime now node20. Node16 has end of life on 11 Sep 2023).

Co-authored-by: Vaclav Petras <wenzeslaus at gmail.com>