Update K-9 Mail and Thunderbird to 10.1 and 11.0b4

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