Moved CHANGED_FILES inside the if condition

Author: srinivasreddy

.github/workflows/reusable-change-detection.yml

@@ -132,9 +132,9 @@ jobs:
           echo "run-cifuzz=false" >> "$GITHUB_OUTPUT"
         fi
 
-        CHANGED_FILES=$(git diff --name-only "origin/$GITHUB_BASE_REF..")
-        # Check if changes are ONLY in configure/Makefile files
         if [ "$GITHUB_BASE_REF" = "main" ]; then
+          CHANGED_FILES=$(git diff --name-only "origin/$GITHUB_BASE_REF..")
+          # Check if changes are ONLY in configure/Makefile files
           if echo "$CHANGED_FILES" | grep -qE '^(configure.*|Makefile.*|.*\.m4)$' && \
               ! echo "$CHANGED_FILES" | grep -qvE '^(configure.*|Makefile.*|.*\.m4)$'; then
             # Only configure/Makefile files changed, skip Windows CI