Fix invalid json caused by a missing comma.

server/handler/test_data/test_get_artists_no_args

@@ -12,7 +12,7 @@
               "name": "13th Floor Elevators"
             }
           ]
-        }
+        },
         {
           "name": "A",
           "artist": [
@@ -25,7 +25,7 @@
               "name": "Anikas"
             }
           ]
-        },
+        }
       ]
     }
   }