json dump dictionary before outputting to github actions (#87)

Author: mingness

scripts/parse_and_validate_properties_txt.py

@@ -147,4 +147,4 @@ def set_output_error(msg):
     contribution.update(props)
 
     print(f"properties dict: {contribution}")  # just for debugging, should do this via logging levels
-    set_output(contribution)
+    set_output(json.dumps(contribution))