[pkg] Update assume to version 2.2.0 (#169)

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "requires-port": "^1.0.0"
   },
   "devDependencies": {
-    "assume": "^1.5.2",
+    "assume": "^2.2.0",
     "browserify": "^16.2.0",
     "mocha": "^6.1.1",
     "nyc": "^13.2.0",