v1.2.1

Fixes

• Track-transition flash could still occasionally slip through with "Hide flash between
  tracks" turned on — the masking window was 1.5s, bumped the window to 3s now :/
• Updated the bundled go-librespot engine to the latest SEKY443/go-librespot-termux
  (upstream devgianlu/go-librespot), pulling in:
  • OAuth 2.0 device authorization flow support (sign in via a code on another device,
    not exposed in the app UI yet).
  • A fix for tracks seeking a few milliseconds on start when they shouldn't.
  • audio/media capability declaration.
  • Connect/TTS proto updates.