[snapshot] Fix Swift compiler version check for SnapshotHelper.swift

[minuscorp]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

Closes #18792

Description

There was a wrong compiler version check for UIImagePNGRepresentation deprecation, which led to a compile error in snapshot

Testing Steps

1. Checkout this branch.
2. Go to snapshot and open the Example.xcodeproj
3. Open SnapshotHelper.swift with a Swift version set at 4.0
4. Compile it.
5. 🚀

[google-cla]

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[joshdholtz]

@googlebot I consent.

[joshdholtz]

Thanks for fixing! ❤️

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.186.0 🚀