Swift 6 support

[honus]

Checklist

• I have looked into the Readme, Examples, and FAQ and have not found a suitable solution or answer.
• I have looked into the API documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Describe the problem you'd like to have solved

Compiling in Swift 6 language mode results in concurrency errors like problems with Sendability of Credentials as discussed in this forum issue from 2022 https://community.auth0.com/t/credentialsmanager-credentials-and-sendability/95271

Describe the ideal solution

The SDK should be updated to compile without errors when used in Swift 6.

Alternatives and current workarounds

Importing with @preconcurrency may be a workaround but could be hiding issues in concurrent code.

Additional context

No response