Update debug to 4.0.0

Author: addaleax

package.json

@@ -21,7 +21,7 @@
   },
   "dependencies": {
     "array-index": "^1.0.0",
-    "debug": "^3.1.0"
+    "debug": "^4.0.0"
   },
   "devDependencies": {
     "bindings": "^1.3.0",