COMP: Point itk-python-package-tag at main for Windows pip fix

ITKPythonPackage#304 (merged 2026-04-13) fixes the Windows wheel
build failure caused by collections.Mapping removal in Python 3.10+.
The fix is on ITKPythonPackage main but not yet in the v5.4.5 tag
that the v5.4.6 action defaults to. Override itk-python-package-tag
to 'main' to pick up the ensurepip bootstrap fix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hjmjohnson

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

@@ -11,6 +11,7 @@ jobs:
   python-build-workflow:
     uses: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction/.github/workflows/build-test-package-python.yml@v5.4.6
     with:
+      itk-python-package-tag: 'main'
       test-notebooks: true
     secrets:
       pypi_password: ${{ secrets.pypi_password }}