[chore] Pin debug to version 2.6.4 (#567)

Author: darrachequesne

package.json

@@ -25,7 +25,7 @@
   "dependencies": {
     "component-emitter": "1.2.1",
     "component-inherit": "0.0.3",
-    "debug": "~2.6.4",
+    "debug": "2.6.4",
     "engine.io-parser": "2.1.0",
     "has-cors": "1.1.0",
     "indexof": "0.0.1",