[clang] [clang][Diagnostics] Make 'note' color CYAN (PR #66997)

[Timm Baeder via cfe-commits]

tbaederr wrote:

I know, this only fixes the problem in the vast majority of cases. I don't know of any tool implementing dynamic background color checking so it can adjust the foreground color though.

This is a one-liner that fixes the problem on terminals with a dark background and the solution also works on light backgrounds. So, basically all of them.

https://github.com/llvm/llvm-project/pull/66997