Log Message:
cmake: updated to 3.20.5

CMake 3.20.5
* gitlab-ci: update macOS jobs to use Xcode 12.5
* cmGlobalVisualStudio10Generator: Move static functions to anonymous namespace
* cmGlobalVisualStudio10Generator: Adopt GetVSInstanceVersion method
* VS: Do not apply '/external:W*' flag table mapping on VS < 16.10
* Tests: Fix xcode version detection for Xcode 13 on ARM
* Help: Add 3.20 release note section for 3.20.{3,4,5}
* ExternalProject: Use ${ref}^0 to avoid MSYS/Cygwin shell substitutions
* CMake: Allow override of unexpected non-flow-control commands