The change introduced in #71 so that we can run the Android build in a
GitHub action, broke the `flutter build appbundle` command to build the
Android version for the Google Play store. This commit should fix this,
so that we can build the Android version in a GitHub Action and for
Google Play.
This commit adds 2 new jobs to the existing "Continuous Delivery" GitHub
Action to test the build of the iOS and Android app.
For this we also had to adjust the "build.gradle" file for the Android
app, so that the test build in the GitHub Action is signed with dummy
credentials, since we do not provide the keystore properties.
- Adjust "Release" section in contributing guide.
- Disable "X" datasource, since it is not working after the latest API
adjustments.
- Update "version" key and "msix_config.msix_version" key in
"pubspec.yaml" file.
- Change user in "AddSourceReddit" widget help text.
- Enable macOS App Sandbox.
- Adjust logo for Windows version.
