Bump minSdk to 23 in RN OSS (#38874)

Summary:
Pull Request resolved: facebook/react-native#38874

In this diff I'm increasing the minSdk of RN Android to 23 to keep it in sync with Meta min sdk

changelog: [Android][Breaking] Increase min sdk version of RN Android to 23

Reviewed By: fkgozali, NickGerleman

Differential Revision: D48177965

fbshipit-source-id: 79f46f6e1674fe9d38dc9dfbe8f0f9a43f39a712

Original-Commit: facebook/react-native@70fcb1e

template/template/android/build.gradle

@@ -3,7 +3,7 @@
 buildscript {
     ext {
         buildToolsVersion = "34.0.0"
-        minSdkVersion = 21
+        minSdkVersion = 23
         compileSdkVersion = 34
         targetSdkVersion = 34
         ndkVersion = "25.1.8937393"