Revert "ci: add wayland platform plugin"

This reverts commit 62cfb7f.

It's wrong: library names need to be manually specified, and it wouldn't
work properly anyway since it doesn't include shell integrations
(linuxdeploy/linuxdeploy-plugin-qt#130).

.github/workflows/main.yml

@@ -64,7 +64,6 @@ jobs:
         chmod +x *.AppImage
         cd dist
         cp ../groundstation-app/images/icon.svg ../groundstation-app.svg
-        export EXTRA_PLATFORM_PLUGINS=wayland
         ../linuxdeploy --appdir ../groundstation-app/AppDir -e ../groundstation-app/AppDir/opt/groundstation-app/bin/groundstation-app -i ../groundstation-app.svg --create-desktop-file --plugin qt -o appimage
       if: matrix.os == 'ubuntu-latest'
     - name: Copy license and readme