Remove unnecessary `pub`

[Ten0]

(non backwards-compatible)

Alternately we could make this return an explicit type so that it's expressable, but I doubt that would actually be necessary for anyone. https://github.com/scylladb/scylla-rust-driver/blob/db8d52893bdef56977872a09f51fda2fa423168f/scylla-cql/src/frame/value.rs#L189

[wprzytula]

@Ten0 This is ridiculously late response, but could you please rebase this on newest main? We'll graciously merge it.