Fix test_entities test

tests/test_elements_worker/test_entities.py

@@ -213,7 +213,7 @@ def test_create_entity(responses, mock_elements_worker):
     assert json.loads(responses.calls[-1].request.body) == {
         "name": "Bob Bob",
         "type": "person",
-        "metas": None,
+        "metas": {},
         "validated": None,
         "corpus": "12341234-1234-1234-1234-123412341234",
         "worker_version": "12341234-1234-1234-1234-123412341234",
@@ -247,7 +247,7 @@ def test_create_entity_with_cache(responses, mock_elements_worker_with_cache):
     assert json.loads(responses.calls[-1].request.body) == {
         "name": "Bob Bob",
         "type": "person",
-        "metas": None,
+        "metas": {},
         "validated": None,
         "corpus": "12341234-1234-1234-1234-123412341234",
         "worker_version": "12341234-1234-1234-1234-123412341234",
@@ -261,7 +261,7 @@ def test_create_entity_with_cache(responses, mock_elements_worker_with_cache):
             type="person",
             name="Bob Bob",
             validated=False,
-            metas=None,
+            metas={},
             worker_version_id=UUID("12341234-1234-1234-1234-123412341234"),
         )
     ]