docs: Update required typescript version (#802)

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

Author: anikeef

README.md

@@ -53,7 +53,7 @@ const { ref, reactive } = VueCompositionAPI
 
 ## TypeScript Support
 
-> TypeScript version **>3.5.1** is required
+> TypeScript version **>4.2** is required
 
 To let TypeScript properly infer types inside Vue component options, you need to define components with `defineComponent`