BUG: Replace master with main as default branch name

Simplify the curl command by setting default values
as separate bash environmental variable explicit setting.

There is no need for a temporary value where a consistent
permanent value is easier to trace.

Author: hjmjohnson

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

@@ -87,8 +87,10 @@ jobs:
     - name: 'Fetch build script'
       run: |
         IPP_DOWNLOAD_GIT_TAG=${{ inputs.itk-python-package-tag }}
+        IPP_DOWNLOAD_GIT_TAG=${IPP_DOWNLOAD_GIT_TAG:=main}
         IPP_DOWNLOAD_ORG=${{ inputs.itk-python-package-org }}
-        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG:=master}/scripts/dockcross-manylinux-download-cache-and-build-module-wheels.sh -O
+        IPP_DOWNLOAD_ORG=${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}
+        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG}/scripts/dockcross-manylinux-download-cache-and-build-module-wheels.sh -O
         chmod u+x dockcross-manylinux-download-cache-and-build-module-wheels.sh
 
     - name: 'Build 🐍 Python 📦 package'
@@ -181,8 +183,10 @@ jobs:
     - name: 'Fetch build script'
       run: |
         IPP_DOWNLOAD_GIT_TAG=${{ inputs.itk-python-package-tag }}
+        IPP_DOWNLOAD_GIT_TAG=${IPP_DOWNLOAD_GIT_TAG:=main}
         IPP_DOWNLOAD_ORG=${{ inputs.itk-python-package-org }}
-        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG:=master}/scripts/dockcross-manylinux-download-cache-and-build-module-wheels.sh -O
+        IPP_DOWNLOAD_ORG=${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}
+        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG}/scripts/dockcross-manylinux-download-cache-and-build-module-wheels.sh -O
         chmod u+x dockcross-manylinux-download-cache-and-build-module-wheels.sh
 
     - name: 'Build 🐍 Python 📦 package'
@@ -267,8 +271,10 @@ jobs:
       if: matrix.python3-minor-version != '8'
       run: |
         IPP_DOWNLOAD_GIT_TAG=${{ inputs.itk-python-package-tag }}
+        IPP_DOWNLOAD_GIT_TAG=${IPP_DOWNLOAD_GIT_TAG:=main}
         IPP_DOWNLOAD_ORG=${{ inputs.itk-python-package-org }}
-        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG:=master}/scripts/macpython-download-cache-and-build-module-wheels.sh -O
+        IPP_DOWNLOAD_ORG=${IPP_DOWNLOAD_ORG:=InsightSoftwareConsortium}
+        curl -L https://raw.githubusercontent.com/${IPP_DOWNLOAD_ORG}/ITKPythonPackage/${IPP_DOWNLOAD_GIT_TAG}/scripts/macpython-download-cache-and-build-module-wheels.sh -O
         chmod u+x macpython-download-cache-and-build-module-wheels.sh
 
     - name: 'Build 🐍 Python 📦 package'