NRL-1050 Only allow snomed category systems

Author: axelkrastek1-nhs

layer/nrlf/core/validators.py

@@ -417,7 +417,7 @@ def _validate_category(self, model: DocumentReference):
             return
 
         coding = model.category[0].coding[0]
-        if coding.system not in ["http://snomed.info/sct", "https://nicip.nhs.uk"]:
+        if coding.system != "http://snomed.info/sct":
             self.result.add_error(
                 issue_code="value",
                 error_code="INVALID_RESOURCE",