Handle bytes in YAML caching

The API client uses response.content from requests when using a schema from a URL, which returns a bytestring, causing AttributeErrors with the YAML caches as it tries to get the file name of the bytestring.

tests/conftest.py

@@ -30,7 +30,9 @@ def cache_yaml(monkeypatch):
         # Create a unique cache key for direct YAML strings
         # and file descriptors
         if isinstance(yaml_payload, str):
-            key = hashlib.md5(yaml_payload.encode("utf-8")).hexdigest()
+            yaml_payload = yaml_payload.encode("utf-8")
+        if isinstance(yaml_payload, bytes):
+            key = hashlib.md5(yaml_payload).hexdigest()
         else:
             key = yaml_payload.name