[ci] Upgrade clang-format version

Author: serge-sans-paille

.github/workflows/style-check.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Run clang-format style check for C/C++ programs.
       uses: jidicula/clang-format-action@v4.11.0
       with:
-        clang-format-version: '17'
+        clang-format-version: '21'
         exclude-regex: 'doctest.h'
   inlining-check:
     runs-on: ubuntu-latest