Copy the headers dict

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: guysmoilov

dagshub/data_engine/client/data_client.py

@@ -185,7 +185,7 @@ def _exec(
         if validate:
             query.validate_params(params if params else {}, self.query_introspection)
         q = gql.gql(query.generate())
-        headers = config.requests_headers
+        headers = dict(config.requests_headers)
         traceparent = None
         if not config.disable_traceparent:
             traceparent = build_traceparent()