[ci] Bump the version of clang-format used in the CI

The version of clang-format we use in the CI to format all
PRs is a bit outdated, leading to some confusion when the
CI job produces different output from what people have locally.

We should decide on a policy for updating this version since
it impacts the whole monorepo, and we should document the version
currently in use somewhere (in the Contributing docs?). We should
also decide on a policy for whether to re-apply clang-format to
the whole codebase whenever we change this version.

Author: ldionne

.github/workflows/pr-code-format.yml

@@ -60,7 +60,7 @@ jobs:
       - name: Install clang-format
         uses: aminya/setup-cpp@v1
         with:
-          clangformat: 18.1.7
+          clangformat: 19.1.5
 
       - name: Setup Python env
         uses: actions/setup-python@v5