01847ef6dd
This changes the Mac and iOS job AMI that we're using to Big Sur (OSX 11.4 update). This includes the following based on https://github.com/aws-lumberyard/o3de/tree/development/scripts/build/build_node/Platform/Mac:
- XCode 12.4
- CMake 3.20.3
Note: As of 86136dd, these builds still fail with the same errors as the nightly build under Catalina. See SPEC-7273 and LYN-4071 for details