Update metadata for com.openathena app, change to AGPLv3.0 License

Required

• The app complies with the inclusion criteria
• All related fdroiddata and RFP issues have been referenced in this merge request
• 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

Suggested

• External repos are added as git submodules instead of srclibs
• Multiple apks for native code (Not Applicable)

---

This MR updates the entry for the com.openathena app. We recently switched the license from GPL3.0-or-later to AGPL-3.0-only. Additionally, a new version of the software, v0.21.0, has been released with significant new features such as automatic elevation model downloading for the user's selected drone image.

This MR does not correspond to an issue on fdroiddata. The original MR for inclusion of this app was: !13839 (merged)