benchmark_config doesn't need .py on setup file

plack/benchmark_config

@@ -2,9 +2,9 @@
   "framework": "plack",
   "tests": [{
     "default": {
-      "setup_file": "setup.py",
+      "setup_file": "setup",
       "port": 8080,
       "sort": 118
     }
   }]
-}
+}