Upgrade SWIG from version 4.0.2 to version 4.1.0 or higher, please!

[N-Dekker]

• Pull request WIP (Not ready): Add GradientImageFilter::OverrideBoundaryCondition(std::unique_ptr<BoundaryConditionType>) #4533 currently fails on both ITK.Linux.Python and ITK.macOS.Python, and it seems to be caused by the lack of std::unique_ptr support by SWIG 4.0.2. Which is the current SWIG version on the ITK master branch:

ITK/Wrapping/Generators/SwigInterface/CMakeLists.txt

Lines 17 to 18 in ac1ebe6

	set(swig_version_min 4.0.2)
	set(ITK_SWIG_VERSION 4.0.2)

std::unique_ptr is an essential utility to prevent memory leaks, as well as multiple delete's on one pointer (which would cause undefined behavior, possibly leading to crashes). It is also useful as function parameter type, to indicate that the function takes ownership of the object that is passed as argument.

SWIG 4.1.0 (released in 2022) appears to be the first version to support std::unique_ptr: https://sourceforge.net/p/swig/news/2022/10/swig-410-released/

The most recent release is version 4.2.1. That version appears to have even more modern C++ support: https://swig.org

Can you please upgrade SWIG? At least to version 4.1.0, but the latest version appears even better 😃

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For the record, SimpleITK is currently at SWIG version 4.1.1: https://github.com/SimpleITK/SimpleITK/blob/8e29d4902cdbc91b03578fa654b06d868b08f03c/SuperBuild/External_Swig.cmake#L22

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