Update CHANGELOG.md (#162)

Author: petea

CHANGELOG.md

@@ -1,5 +1,6 @@
 # 6.2.2 (2022-5-27)
 - Prevent build errors for GoogleSignInSwift when using Swift Package Manager. ([#157](https://github.com/google/GoogleSignIn-iOS/pull/157))
+- Prevent a build error on Xcode 12 and earlier. ([#158](https://github.com/google/GoogleSignIn-iOS/pull/158))
 
 # 6.2.1 (2022-5-19)
 - Use `GoogleSignInSwiftSupport` as the name of the Swift support CocoaPod. ([#137](https://github.com/google/GoogleSignIn-iOS/pull/137))