fix(predictions): use serial queue for WebSocketSession delegate queue

[thisisabhash]

Issue #

Customers have reported receiving intermittent InvalidSignatureException during liveness checks.

Description

According to Apple docs, URLSession delegate queue should use a serial queue for delegate and completion handler callbacks. This PR updates the URLSession initializer with a serial queue.
Also, calls to WebSocketSession object APIs are put under a serial queue as well.

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.