[github] Label PRs touching CMake-related files with the 'cmake' tag (#66247)

Author: ldionne

.github/new-prs-labeler.yml

@@ -362,6 +362,11 @@ debuginfo:
 github:workflow:
   - .github/workflows/**
 
+cmake:
+  - cmake/**
+  - llvm/cmake/**
+  - runtimes/**
+
 flang:driver:
   - flang/tools/flang-driver/**
   - flang/unittests/Frontend/**
@@ -381,15 +386,12 @@ backend:m68k:
 
 libc++:
   - libcxx/**
-  - runtimes/**
 
 libc++abi:
   - libcxxabi/**
-  - runtimes/**
 
 libunwind:
   - libunwind/**
-  - runtimes/**
 
 objectyaml:
   - llvm/include/llvm/ObjectYAML/**