[Bug] Type checker allow borrow of tuple as function return type signature

[JakeSilverman]

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🐛 Bug

Internal move compiler error caused by below snipped

To reproduce

fun ret_borrow_tup(): &(u64, u64) {
    abort 0
}

Expected Behavior

This should result in a compiler error that is caught gracefully.

System information

Please complete the following information:

• Aptos Core Version: 7.3.0
• Rust Version: 1.87.0
• Computer OS: Mac OS 15.5

Additional context

Add any other context about the problem here.