Prevent throwing of error for unsupported tags

[mikekelly]

I'm handling a cbor message that is tagged with a value that's not supported and so trying to decode the message throws this error:

https://github.com/valpackett/SwiftCBOR/blob/edc01765cf6b3685bb622bb09242ef5964fb991b/Sources/Decoder/UnkeyedDecodingContainer.swift#L228

What's the easiest way for me to patch this so that it defaults to handling as if it was a bytestring?