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

@@ -9,7 +9,7 @@ jobs:
       itk-module-deps: 'MinimalPathExtraction@a93af5398906630cd3096fd49375216483c37ff2'
 
   python-build-workflow:
-    uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-package-python.yml@main
+    uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-package-python.yml@ghcr-mirror-dockcross-images
     with:
       itk-module-deps: 'InsightSoftwareConsortium/ITKMinimalPathExtraction@a93af5398906630cd3096fd49375216483c37ff2'
     secrets: