COMP: Bump to minimum CMake 3.16.3
ENH: Bump ITK and replace http with https using script
DOC: Update copyright assignment to NumFOCUS
STYLE: Remove redundant void argument lists
STYLE: Prefer = default to explicitly trivial implementations
ENH: Update enums from recent enum changes in ITK
ENH: Add .gitattributes to allow running ITK clang-formatting scripts
COMP: apply split between threads and work units in ITK5