Bump date-fns from 2.19.0 to 2.20.1

Bumps [date-fns](https://github.com/date-fns/date-fns) from 2.19.0 to 2.20.1.
- [Release notes](https://github.com/date-fns/date-fns/releases)
- [Changelog](https://github.com/date-fns/date-fns/blob/master/CHANGELOG.md)
- [Commits](https://github.com/date-fns/date-fns/compare/v2.19.0...v2.20.1)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -10,7 +10,7 @@
     "test": "jest"
   },
   "dependencies": {
-    "date-fns": "^2.19.0",
+    "date-fns": "^2.20.1",
     "date-fns-tz": "^1.1.3",
     "ics": "^2.27.0",
     "mongoose": "^5.12.3",