Fix wrong Core version for M61 (#4608)

Author: ryanwilson

FirebaseCore/CHANGELOG.md

@@ -1,7 +1,7 @@
 # Unreleased
   [changed] Directory structure reorganization without functional changes.
 
-# v6.4.0 -- M61
+# v6.5.0 -- M61
 - [added] Updated the binary distributions to include arm64e slices. See
   https://developer.apple.com/documentation/security/preparing_your_app_to_work_with_pointer_authentication.
   Support for the open source libraries is now included in the zip and Carthage