fix: handle scenario when there are no changes in v2.json (#793)

Author: andreaangiolillo

.github/workflows/release-spec.yml

@@ -168,6 +168,8 @@ jobs:
             
             export bump_release='false'
             changed_lines=$(git diff --numstat openapi/v2.json | awk '{print $1}')
+            # Default to 0 if empty
+            changed_lines=${changed_lines:-0}
             if [ "${changed_lines}" -gt 1 ]; then
               export bump_release='true'
             fi