Add an "Upgrade clang" step

In the current windows-latest (windows-2022) image, the installed Clang
is version 16, but the Visual Studio STL requires Clang version 17 or
later. The "Upgrade clang" workaround is recommended in
actions/runner-images#10001 (comment).

.github/workflows/ci-windows.yml

@@ -45,6 +45,8 @@ jobs:
         codec-dav1d: 'LOCAL'
         codec-rav1e: 'LOCAL'
 
+    - name: Upgrade clang
+      run: choco upgrade llvm
     - name: Build aom
       if: steps.setup.outputs.ext-cache-hit != 'true'
       working-directory: ./ext