ENH: Bump default ITK_PACKAGE_VERSION to v6.0b01

As we release ITK 6.

Author: thewtex

scripts/dockcross-manylinux-set-vars.sh

@@ -19,7 +19,7 @@
 
 # ITKPythonBuilds archive tag to use for ITK build artifacts.
 #   See https://github.com/insightSoftwareConsortium/ITKpythonbuilds for available tags.
-ITK_PACKAGE_VERSION=${ITK_PACKAGE_VERSION:=v5.4.0}
+ITK_PACKAGE_VERSION=${ITK_PACKAGE_VERSION:=v6.0b01}
 
 # Github organization for fetching ITKPythonPackage build scripts
 ITKPYTHONPACKAGE_ORG=${ITKPYTHONPACKAGE_ORG:=InsightSoftwareConsortium}