sinon@6.3.5

Fixes vulnerable just-extend

Author: Tyriar

addons/xterm-addon-ligatures/package.json

@@ -38,7 +38,7 @@
     "@types/sinon": "^5.0.1",
     "axios": "^0.18.0",
     "mkdirp": "0.5.5",
-    "sinon": "^6.1.3",
+    "sinon": "6.3.5",
     "yauzl": "^2.10.0"
   },
   "peerDependencies": {