install llvm 15

Change-Id: I56afba39419063b8c420aac85e61c8c2414c5ac5

Author: rdementi

.github/workflows/macos-scan-build.yml

@@ -30,6 +30,10 @@ jobs:
             exit 1
           }
 
+    - name: install brew
+      run: |
+        brew install llvm@15
+
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       with:
         submodules: recursive