Remove upgrade script

When using the mono repo each module had to check its own dependencies
for upgrades. We have replaced this with Renovate. So this script can be
removed.

Author: mpkorstanje

package.json

@@ -32,7 +32,6 @@
     "test": "npm run mocha",
     "mocha": "mocha",
     "prepublishOnly": "npm run build",
-    "upgrade": "npm-check-updates --upgrade",
     "eslint": "eslint --ext ts,tsx --max-warnings 0 src test",
     "eslint-fix": "eslint --ext ts,tsx --max-warnings 0 --fix src test",
     "pretty-quick": "pretty-quick --staged"