Add changelog

Author: pashanka

FirebaseAuth/CHANGELOG.md

@@ -4,6 +4,7 @@
   for decoding `nil` values. (#14212)
 - [fixed] Address Xcode 16.2 concurrency compile time issues. (#14279)
 - [fixed] Fix handling of cloud blocking function errors. (#14052)
+- [fixed] Fix phone auth flow to skip RCE verification if appVerificationDisabledForTesting is set. (#14242)
 
 # 11.6.0
 - [added] Added reCAPTCHA Enterprise support for app verification during phone