Box complains of duplicate slashes so remove this slash.

bobbyshaw · bobbyshaw · commit 75a2239d9867 · 2017-02-15T20:30:40.000Z
diff --git a/box.json b/box.json
@@ -23,7 +23,7 @@
         "tests"
       ],
       "in": [
-        "vendor/"
+        "vendor"
       ]
     }
   ],
