Add Ci task to build a debug app on branches that are not master and build a fdroid signed version only when building on master

Took 5 minutes

.gitlab-ci.yml

@@ -41,6 +41,19 @@ build_android_fdroid:
     when: on_success
     paths:
       - build/app/outputs/apk/release/app-release.apk
+  only:
+    - master
+
+build_android_debug:
+  stage: coverage
+  script:
+    - flutter build apk --debug
+  artifacts:
+    when: on_success
+    paths:
+      - build/app/outputs/apk/release/app-debug.apk
+  except:
+    - master
 
 pages:
   stage: publish