CI: use sage develop branch

The meson build infrastructure has been merged in Sage 9.8.beta4.  The
develop branch, which updates on every beta release, can thus be now
used for running the meson-python tests.

Author: mkoeppe

.github/workflows/sage.yml

@@ -125,8 +125,7 @@ jobs:
 
   test:
     # https://github.com/sagemath/sage/blob/develop/.github/workflows/docker.yml
-    # Use branch u/mkoeppe/numpy_1_23_x__scipy_1_9_x for a fix for uppercase github repo names (FFY00)
-    uses: sagemath/sagetrac-mirror/.github/workflows/docker.yml@u/mkoeppe/numpy_1_23_x__scipy_1_9_x
+    uses: sagemath/sagetrac-mirror/.github/workflows/docker.yml@develop
     with:
       tox_system_factors: ${{ needs.build.outputs.systems }}
       tox_packages_factors: >-
@@ -137,18 +136,11 @@ jobs:
       extra_sage_packages: "liblzma bzip2 libffi python3 ninja_build"
       # Sage distribution packages to build
       targets: SAGE_CHECK=no SAGE_CHECK_PACKAGES="meson_python" python_build meson_python
-      # Standard setting: Test the current beta release of Sage:
       sage_repo: sagemath/sage
       sage_ref: develop
       upstream_artifact: upstream
       sage_trac_git: https://github.com/sagemath/sagetrac-mirror.git
-      # Temporarily test on the branch from sage ticket https://trac.sagemath.org/ticket/34081 (scipy 1.9.x)
-      # (this is a no-op after that ticket is merged)
-      sage_trac_ticket: 34081
-      # Docker targets (stages) to tag
       docker_targets: "with-targets"
-      # We prefix the image name with the SPKG name ("meson-python-") to avoid the error
-      # 'Package "sage-docker-..." is already associated with another repository.'
       docker_push_repository: ghcr.io/${{ github.repository }}/meson-python-
     needs: [build]