Update to 2.8.3
    
    - Fix reading “include” instructions in Compose files and observe XCOMPOSEFILE
      (Resolves: https://github.com/mike-fabian/ibus-typing-booster/issues/93)
    - Fix right-to-left detection for LC_MESSAGES=C
      (Resolves: https://github.com/mike-fabian/ibus-typing-booster/issues/97)
    - GUI tests added thanks to Takao Fujiwara
    - Update UnicodeData.txt to Unicode 13.0.0
    - Translation updates for it, hu, tr, pt_BR