Fix CI plugin val step, now needs gui related dev libs

.github/workflows/build.yml

@@ -1048,7 +1048,7 @@ jobs:
           sudo dpkg -i kxstudio-repos_10.0.3_all.deb
           sudo apt-get update -qq
           # build-deps
-          sudo apt-get install -yqq liblo-dev
+          sudo apt-get install -yqq libdbus-1-dev libgl1-mesa-dev liblo-dev libx11-dev libxcursor-dev libxext-dev libxrandr-dev
           # runtime testing
           sudo apt-get install -yqq carla-git lilv-utils lv2-dev lv2lint valgrind xvfb
       - name: Set up ccache