Remove devDependency on delay So test file can be imported by other modules

packages/keyv/package.json

@@ -31,7 +31,6 @@
   "devDependencies": {
     "ava": "^0.19.1",
     "coveralls": "^2.13.1",
-    "delay": "^2.0.0",
     "eslint-config-xo-lukechilds": "^1.0.0",
     "nyc": "^10.3.2",
     "xo": "^0.19.0"

packages/keyv/test/helpers/test-store.js

@@ -1,9 +1,10 @@
 /* eslint-disable ava/no-ignored-test-files */
 
 const test = require('ava');
-const delay = require('delay');
 const Keyv = require('../../');
 
+const delay = ms => new Promise(resolve => setTimeout(resolve, ms));
+
 const testStore = store => {
 	test.serial('.set(key, value) returns a Promise', t => {
 		const keyv = new Keyv({ store });