Bump react-datepicker from 4.16.0 to 4.21.0 #471

Job	Run time
install	1m 13s
install	1m 13s
jest	1m 5s
jest	1m 5s
cypress-run (Incidents/incidents.spec.js)	9m 47s
cypress-run (Incidents/incidents.spec.js)	9m 47s
cypress-run (Query/query.spec.js)	7m 41s
cypress-run (Query/query.spec.js)	7m 41s
cypress-run (Search/search.spec.js)	4m 42s
cypress-run (Search/search.spec.js)	4m 42s
cypress-run (Settings/settings.spec.js)	17m 41s
cypress-run (Settings/settings.spec.js)	10m 43s
cypress-run (app.spec.js)	5m 45s
cypress-run (app.spec.js)	5m 45s
	1h 28m 50s

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