WIP: Test GHCR mirror pre-pull for dockcross images

Temporarily point python-build-workflow at the
ghcr-mirror-dockcross-images branch of
ITKRemoteModuleBuildTestPackageAction to test the
pre-pull step with GHCR fallback logic.

See: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction#124

Author: hjmjohnson

.github/workflows/build-test-package.yml

@@ -6,6 +6,6 @@ jobs:
   cxx-build-workflow:
     uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-cxx.yml@v6.0b02
   python-build-workflow:
-    uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-package-python.yml@v6.0b02
+    uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-package-python.yml@ghcr-mirror-dockcross-images
     secrets:
       pypi_password: ${{ secrets.pypi_password }}