Downgrade node-fetch.

Fixes `--experimental-modules` tests for Node.js < v10.2.0. See node-fetch/node-fetch#502.

Author: jaydenseric

changelog.md

@@ -5,6 +5,7 @@
 ### Patch
 
 - Fix event listeners added in v1.1.1 to be compatible with Node.js < v10.
+- Downgrade `node-fetch` to fix `--experimental-modules` tests for Node.js < v10.2.0 (see [bitinn/node-fetch#502](https://github.com/bitinn/node-fetch/issues/502)).
 
 ## 1.1.1
 

package.json

@@ -50,7 +50,7 @@
     "koa": "^2.5.3",
     "koa-bodyparser": "^4.2.1",
     "lint-staged": "^7.3.0",
-    "node-fetch": "^2.2.0",
+    "node-fetch": "~2.1.2",
     "prettier": "^1.14.3",
     "tap": "^12.0.1",
     "watch": "^1.0.2"