Add 3-pythonscript-cython-only test to CI

Author: touilleMan

.github/workflows/build.yml

@@ -75,6 +75,7 @@ jobs:
           python tests/run.py 0-gdscript --build-dir build/ -- --headless
           python tests/run.py 1-gdextension --build-dir build/ -- --headless
           python tests/run.py 2-pythonscript-init --build-dir build/ -- --headless
+          python tests/run.py 3-pythonscript-cython-only --build-dir build/ -- --headless
       # - name: 'Generate artifact archive'
       #   run: meson compile -C build/ release
       # - name: 'Export release artifact'
@@ -131,6 +132,7 @@ jobs:
           python tests/run.py 0-gdscript --build-dir build/ --godot-binary "${{ matrix.PLATFORM }}:" -- --headless
           python tests/run.py 1-gdextension --build-dir build/ --godot-binary "${{ matrix.PLATFORM }}:" -- --headless
           python tests/run.py 2-pythonscript-init --build-dir build/ --godot-binary "${{ matrix.PLATFORM }}:" -- --headless
+          python tests/run.py 3-pythonscript-cython-only --build-dir build/ --godot-binary "${{ matrix.PLATFORM }}:" -- --headless
       # - name: 'Install Mesa3D OpenGL'
       #   shell: bash
       #   run: |