ci: use format string for zsh

Author: star0202

.github/workflows/cpp.yml

@@ -17,4 +17,4 @@ jobs:
           clangformat: 18.1.6
       - name: Run clang-format
         run: clang-format-18 **/*.cpp **/*.hpp -n --Werror
-        shell: zsh
+        shell: zsh {0}