Add missing license value to isomorphic-unfetch. Fixes #128.

Author: developit

packages/isomorphic-unfetch/package.json

@@ -11,6 +11,7 @@
   "browser": "browser.js",
   "main": "index.js",
   "types": "index.d.ts",
+  "license": "MIT",
   "dependencies": {
     "node-fetch": "^2.2.0",
     "unfetch": "^4.0.0"