adjust typescript def for setExtendedProp. fixes #4679

CHANGELOG.md

@@ -2,6 +2,7 @@
 next
 ----
 
+- adjust typescript def for setExtendedProp (#4679)
 - googleCalendarApiKey added to typescript options definition (#4772)
 - sourcemaps removed from dist (accidentally included in previous version)
 - moment/luxon formatting same-day range with dash (#4686)

packages/core/src/api/EventApi.ts

@@ -61,7 +61,7 @@ export default class EventApi {
     }
   }
 
-  setExtendedProp(name: string, val: string) {
+  setExtendedProp(name: string, val: any) {
     this.mutate({
       extendedProps: { [name]: val }
     })