ci:uninstall cmake before install

Author: luoliwoshang

.github/workflows/build-macos.yml

@@ -79,6 +79,7 @@ jobs:
           rm -rf llvm-project
           make llvm-source
           # install dependencies
+          brew uninstall cmake || true
           HOMEBREW_NO_AUTO_UPDATE=1 brew install cmake ninja
           # build!
           make llvm-build