chore: Make pipeline fail if non-free deps are found

.gitlab-ci.yml

@@ -75,7 +75,8 @@ test_nonfree_code:
   stage: test-after-build
   image: registry.funkwhale.audio/funkwhale/ci/android-fdroidserver
   script:
-    - fdroid scanner -v app/build/outputs/apk/debug/app-debug.apk
+    - fdroid scanner -v app/build/outputs/apk/debug/app-debug.apk | tee output.txt
+    - ! grep "CRITICAL" output.txt
 
 coverage:
   stage: visualize