Add new application: Canta

Required

• The app complies with the inclusion criteria
• The original app author has been notified (I'm the author)
• All related fdroiddata and RFP issues have been referenced in this merge request (Has no issues open)
• Builds with fdroid build

Strongly Recommended

• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure
• Releases are tagged
  • I have a problem with update-check workflow though and seek help

Suggested

• External repos are added as git submodules instead of srclibs (not using any external repos)
• Enable Reproducible Builds
  • I'm not sure how to apply this actually. Releases on my GitHub page are already signed with my key. Not sure if current properties are enough ...
• Multiple apks for native code (not using any native code)