M134: update GMA version in readme (#1390)

* m134 release update

* gma version update

---------

Co-authored-by: Cynthia Jiang <[email protected]>

Author: cynthiajoan

release_build_files/readme.md

@@ -638,7 +638,7 @@ code.
       builder failed to create PhoneAuthOptions with certain compiler settings.
     - Auth (iOS): Fixed an issue where functions that return AuthResult
       were not including updated credentials when encountering errors.
-    - GMA (iOS): Updated dependency to Google-Mobile-Ads-SDK version 10.7.0.
+    - GMA (iOS): Updated dependency to Google-Mobile-Ads-SDK version 10.8.0.
     - GMA (Android): Updated dependency to play-services-ads version 22.2.0.
     - Remote Config (Desktop): Additional fix for handling of non-English time
       zone names on Windows.