[gnome-music/wip/jfelder/ci-fedora] ci: Ensure to use a fedora image for the check stage

[Jean Felder <jfelder src gnome org>]

commit 096c77e8333773f1d15086c3e352c2dbd834ffed
Author: Jean Felder <jfelder src gnome org>
Date:   Thu Jun 23 13:02:45 2022 +0200

    ci: Ensure to use a fedora image for the check stage
    
    flake8 and mypy stages rely on the use of dnf.

 .gitlab-ci.yml | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fdbf4bad5..5a22033a5 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -25,12 +25,14 @@ nightly:
 
 flake8:
   stage: check
+  image: registry.fedoraproject.org/fedora:latest
   script:
     - dnf install -y python3-flake8
     - flake8 --ignore E402,W503 --show-source gnomemusic/
 
 mypy:
   stage: check
+  image: registry.fedoraproject.org/fedora:latest
   script:
     - dnf install -y python3-mypy
     - mypy --ignore-missing-imports --disallow-incomplete-defs gnomemusic