Update dependency node-ical to v0.20.0

Author: renovate[bot]

package-lock.json

@@ -26,7 +26,7 @@
     "humanize-duration": "3.32.1",
     "lodash.clonedeep": "4.5.0",
     "moment-timezone": "0.5.45",
-    "node-ical": "0.16.1"
+    "node-ical": "0.20.0"
   },
   "scripts": {
     "test": "standard && npm run ts:lint && env TZ=UTC jest",