Log Message:
audio/fasttracker2: Update to 1.68

Changes since v1.66

v1.68 - 29.06.2023
- Windows: On double-click of file associated with program, de-minimize window
  (if minimized) and set input focus.
- De-minimize window (if minimized) and set focus after drag n' drop of file
- Windows/macOS: Updated SDL to v2.28.0

v1.67 - 25.04.2023
- The song-to-WAV export screen now defaults to the tracker's bit depth and
  audio rate. This was actually the behavior for earlier versions of the FT2
  clone, but I decided to change it back.
- The song-to-WAV exporter now allows rates up to 384kHz
- Alpha-based fade in for the about screen content (who cares..? :-)
- Some small text string changes (config and song-to-WAV export screen)
- Windows/macOS: Updated SDL to v2.26.5