Make /keys/ return correct Server version

synapse/http/server_key_resource.py

@@ -50,6 +50,7 @@ class LocalKey(Resource):
 
     def __init__(self, hs):
         self.hs = hs
+        self.version_string = hs.version_string
         self.response_body = encode_canonical_json(
             self.response_json_object(hs.config)
         )
@@ -82,7 +83,10 @@ class LocalKey(Resource):
         return json_object
 
     def render_GET(self, request):
-        return respond_with_json_bytes(request, 200, self.response_body)
+        return respond_with_json_bytes(
+            request, 200, self.response_body,
+            version_string=self.version_string
+        )
 
     def getChild(self, name, request):
         if name == '':