Build files out of date for OSX

[illeatmyhat]

When building on OSX Big Sur, builds will fail due to the error:

CMake Error at build_files/cmake/platform/platform_apple.cmake:159 (message):
  Python executable missing:
  /Users/user/Documents/blender/blender/../lib/darwin/python/bin/python3.7m
Call Stack (most recent call first):
  CMakeLists.txt:896 (include)

The solution appears to be to rebase to the current master. Specifically, these lines are out of date in this repo:
https://github.com/blender/blender/blob/7655cc45eb9256f699d40be105cbb6fe93f2e119/build_files/cmake/platform/platform_apple.cmake#L136-L157

[winthropchan]

I just spent a bit of time to fix this and update the build with the latest addon versions. I tested this on OSX Big Sur and was able to build it successfully. I submitted a pull request for my fixes.