Unset the returnFormat for SPARQLStore

Author: white-gecko

rdflib/plugins/stores/sparqlstore.py

@@ -162,7 +162,7 @@ def __init__(
         sparql11: bool = True,
         context_aware: bool = True,
         node_to_sparql: _NodeToSparql = _node_to_sparql,
-        returnFormat: SUPPORTED_FORMATS = "xml",  # noqa: N803
+        returnFormat: SUPPORTED_FORMATS | None = None,  # noqa: N803
         method: SUPPORTED_METHODS = "GET",
         auth: tuple[str, str] | None = None,
         **sparqlconnector_kwargs,