Update CHANGELOG.md for Firebase auth 10.13.0 release (#11607)

Author: renkelvin

FirebaseAuth/CHANGELOG.md

@@ -1,5 +1,6 @@
 # 10.13.0
 - [added] Added reCAPTCHA verification support in email authentication flows. (#11231)
+- [fixed] Fixed a compilation error regression introduced in 10.12.0 building iOS App Extensions. (#11537)
 
 # 10.12.0
 - [added] Added support to Firebase Auth to enroll and sign in a user with