use old and new fnames

.github/workflows/clang-format.yml

@@ -26,10 +26,11 @@ jobs:
         run: |
           for fname in $(find . -name '*.cpp' -o -name '*.h')
           do 
+            old_fname="${fname}"
             new_fname="$(echo -e "${fname}" | tr ' ' '_')"
             new_fname="$(echo -e "${new_fname}" | tr 'A-Z' 'a-z')"
             echo $new_fname
-            git mv $fname $new_fname
+            git mv $old_fname $new_fname
           done
           git commit -am "formatting filenames $GITHUB_SHA" ||  true
       - name: Clang Formatter