CMAKE_CXX_STANDARD BOOL?

.github/workflows/cxx-python.yml overrules the C++ Standard version used to compile the project, by saying `-DCMAKE_CXX_STANDARD:BOOL=20`:

https://github.com/InsightSoftwareConsortium/ITK-Wasm/blob/3818ff25dd1eec8ea87a148ba1b30aef0a48b47a/.github/workflows/cxx-python.yml#L20

Three questions:

- Why is the C++ Standard version specified as a Boolean value? That looks like a bug.
- Is it useful to specify its type anyway? Wouldn't `-DCMAKE_CXX_STANDARD=20` work just fine?
- Wouldn't it be preferable to "hard-code" the C++ Standard version in the CMakeLists.txt, instead of specifying this "on the fly", at the yml/cmake command-line?