fix: update taxon observers route tests to lowercase

Co-authored-by: Jacques Fize <[email protected]>

Author: edelclaux

backend/geonature/tests/test_synthese.py

@@ -1302,14 +1302,14 @@ def test_taxon_observer(self, synthese_data, users):
                     "date_min": "Wed, 02 Oct 2024 11:22:33 GMT",
                     "media_count": 0,
                     "observation_count": 3,
-                    "observer": "Bob Bobby",
+                    "observer": "bob bobby",
                 },
                 {
                     "date_max": "Thu, 03 Oct 2024 08:09:10 GMT",
                     "date_min": "Wed, 02 Oct 2024 11:22:33 GMT",
                     "media_count": 0,
                     "observation_count": 3,
-                    "observer": "Administrateur Test",
+                    "observer": "administrateur test",
                 },
             ],
             "page": 1,