ci: build ITK with C++20

Author: thewtex

.github/workflows/cxx-python.yml

@@ -17,6 +17,7 @@ jobs:
     with:
       itk-module-deps: '[email protected]'
       ctest-options: '-E itkPipelineTest'
+      itk-cmake-options: '-DCMAKE_CXX_STANDARD:BOOL=20'
 
   #python-build-workflow:
     ## itk-wasm branch