[GRASS-git] [OSGeo/grass] 14927e: docker alpine: CI update for `set-output` command ...

[Markus Neteler]

  Branch: refs/heads/releasebranch_8_2
  Home:   https://github.com/OSGeo/grass
  Commit: 14927ee328512774afeb9473010ece4972210a7d
      https://github.com/OSGeo/grass/commit/14927ee328512774afeb9473010ece4972210a7d
  Author: Markus Neteler <neteler at gmail.com>
  Date:   2023-04-18 (Tue, 18 Apr 2023)

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

  Log Message:
  -----------
  docker alpine: CI update for `set-output` command (#2921)

Currently (e.g. https://github.com/OSGeo/grass/actions/runs/4718450552/jobs/8368064252#step:8:9512) the following warning shows up:

   build and push alpine for branch
   The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see:
   https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

This PR attempts to update it accordingly.