fix(appimage): avoid gtk errors when starting gui

AppImageBuilder.yml

@@ -58,6 +58,7 @@ AppDir:
       - python3-gi-cairo
       - python3-pylibacl
       - python3-vdf
+      - shared-mime-info # required for gui
     exclude:
       - gcc*
       - libblkid*
@@ -97,7 +98,6 @@ AppDir:
       # It must precede an existing $PYTHONPATH to work.
       PYTHONPATH: "${APPDIR}/usr/lib/python3/dist-packages:${PATH}:${PYTHONPATH}"
       GI_TYPELIB_PATH: "${APPDIR}/usr/lib/girepository-1.0:${APPDIR}/usr/lib/{{APPIMAGE_ARCH}}-linux-gnu/girepository-1.0"
-      XDG_DATA_DIRS: "${XDG_DATA_DIRS}:/usr/share"
 
 AppImage:
   arch: "{{APPIMAGE_ARCH}}"