Merge branch 'android-updates'

Adds a button to install user certificates and updates the target SDK
version for Android 11 (and the related deprecation fixes), which will
be mandatory later this year.

The release also includes an older commit that changed how DNS servers
are applied to TUN devices (cd10ae2ff050 ("android: Explicitly apply DNS
servers to the TUN device")).

Also added are metadata for F-Droid.