Use retained CUDA 12 milestone for source distributions

Signed-off-by: Ralf W. Grosse-Kunstleve <rgrossekunst@nvidia.com>

Author: rwgk

.github/workflows/test-sdist-linux.yml

@@ -63,14 +63,8 @@ jobs:
         with:
           python-version: "3.12"
 
-      - name: Install build and CI tools
-        run: python -m pip install build -e ./ci
-
-      - name: Prepare local maintenance SCM milestone
-        if: ${{ fromJSON(inputs.bindings-package).release_status == 'maintenance' }}
-        run: |
-          python -m ci.tools.bindings_scm_version \
-            --package-root "${BINDINGS_ROOT}" --sha "${{ github.sha }}"
+      - name: Install build tools
+        run: python -m pip install build
 
       # Pure Python packages -- no CTK needed.
       - name: Build cuda.pathfinder sdist and wheel-from-sdist

.github/workflows/test-sdist-windows.yml

@@ -76,14 +76,8 @@ jobs:
         if: ${{ env.BUILD_BINDINGS == 'true' || env.BUILD_CORE == 'true' }}
         uses: step-security/msvc-dev-cmd@22c98154b708dbd743e6f27a933cf6ceba3305c4  # v1.13.1
 
-      - name: Install build and CI tools
-        run: python -m pip install build -e ./ci
-
-      - name: Prepare local maintenance SCM milestone
-        if: ${{ fromJSON(inputs.bindings-package).release_status == 'maintenance' }}
-        run: |
-          python -m ci.tools.bindings_scm_version \
-            --package-root "${BINDINGS_ROOT}" --sha "${{ github.sha }}"
+      - name: Install build tools
+        run: python -m pip install build
 
       # Pure Python packages -- no CTK needed.
       - name: Build cuda.pathfinder sdist and wheel-from-sdist