[wesnoth-commits] [wesnoth/wesnoth] 97bca4: Update flatpak docker image to newer runtime.

[Pentarctagon]

  Branch: refs/heads/master
  Home:   https://github.com/wesnoth/wesnoth
  Commit: 97bca421e768436f0be245737de84e6ea6e0aa4b
      https://github.com/wesnoth/wesnoth/commit/97bca421e768436f0be245737de84e6ea6e0aa4b
  Author: Pentarctagon <pentarctagon at tutamail.com>
  Date:   2021-02-17 (Wed, 17 Feb 2021)

  Changed paths:
    M utils/dockerbuilds/CI/Dockerfile-base-flatpak

  Log Message:
  -----------
  Update flatpak docker image to newer runtime.

Also change the base image to Ubuntu 20.04 and remove the PPA providing a newer flatpak version.