[GRASS-git] [OSGeo/grass] 9e8814: GitHub action CI: drop ubuntu-16.04 (#1254)

[Markus Neteler]

  Branch: refs/heads/releasebranch_7_8
  Home:   https://github.com/OSGeo/grass
  Commit: 9e8814a1f18cf3ee40e030798c2d647cf3ad226c
      https://github.com/OSGeo/grass/commit/9e8814a1f18cf3ee40e030798c2d647cf3ad226c
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2021-01-23 (Sat, 23 Jan 2021)

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

  Log Message:
  -----------
  GitHub action CI: drop ubuntu-16.04 (#1254)

Since ubuntu-16.04 is rather dated, drop it in GitHub action CI.