The recent update of the GoogleSignIn iOS SDK to v7.1.0 seems to have broken our CI in 2 ways:

1. Mac_x64 check_podspecs - Build failure.
2. Mac_arm64 ios_platform_tests_shard_1 master - Build failure.

As a mitigation, the version of the SDK has been pinned to 7.0.0, here:

• [google_sign_in_ios] Pins GoogleSignIn to 7.0.0 in podspec. packages#6430

But the pin needs to be cleaned up.

Earlier description

The "Mac_x64 check_podspecs" seems to be consistently failing in flutter/packages; there's a warning while checking google_sign_in_os:

 - WARN  | swift: The validator used Swift `4.0` by default because no Swift
version was specified. To specify a Swift version during validation, add the
`swift_versions` attribute in your podspec. Note that usage of a `.swift-version`
file is now deprecated.

(Example of the Failure.)

In the meantime, --allow-warnings has been added to podspec_check_command.dart to unblock the tree. (Please, revert flutter/packages#6416 as part of this fix!) Reverted, as the change exposed another issue, mentioned below!