docs: bump supported React Native version to 0.69.x

Author: edeckers

README.md

@@ -25,7 +25,7 @@ npm install react-native-blob-courier
 - Android Gradle Plugin >= 7.5.1
 - iOS >= 12.4
 - JDK >= 11
-- React Native >= 0.68.x
+- React Native >= 0.69.x
 
 _Note: you may have success with earlier versions of React Native but these are neither tested nor supported._