Fix mock document.

Author: led02

test/hermes_test/model/types/conftest.py

@@ -40,7 +40,7 @@ def compact(cls, base_url: str = "http://spam.eggs/", embed_vocabulary: bool = T
         :returns: The rendered compact document.
         """
         return {
-            "@context": [cls.vocabulary(base_url) if embed_vocabulary else base_url],
+            "@context": cls.vocabulary(base_url) if embed_vocabulary else base_url,
 
             "spam": "bacon",
             "ham": f"{base_url}identifier",