Install and use clang-15

Author: rjogrady

.github/workflows/ci.yaml

@@ -22,7 +22,12 @@ jobs:
     runs-on: ${{ matrix.os }}
     name: "Build/Test ${{ matrix.os }} ${{ matrix.compiler.name }} ${{ matrix.config }}"
     steps:
-      - name: Setup Python
+      - name: Install clang
+        run: |
+          sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-15 100
+          sudo update-alternatives --set clang /usr/bin/clang-15
+
+     - name: Setup Python
         uses: actions/setup-python@v5
         with:
           python-version: "3.12"