don't overwrite yaml data

Author: jukent

.github/workflows/update-resource-gallery.yaml

@@ -92,10 +92,15 @@ jobs:
           import json
 
           with open(submission_file, 'r') as file:
-              data = json.load(file)
+              new_data = json.load(file)
 
+          with open(resource_gallery_file, 'r') as yaml_file:
+              existing_data = yaml.load(yaml_file) or []
+          
+          existing_data.append(new_data)
+          
           with open(resource_gallery_file, 'w') as yaml_file:
-              yaml.dump(data, yaml_file)
+              yaml.dump(existing_data, yaml_file, default_flow_style=False)
 
       - name: Run pre-commit hooks
         run: |