use `TransactionPruned` in `TxBlobEntry`
`TxBlobEntry` should be a pruned transaction:
https://github.com/SyntheticBird45/cuprate/blob/265fb3e895e97b3027651121b646d0f202fd3b19/net/monero-wire/src/messages/common.rs#L103

However monero-rs does not currently support pruned transactions. So for now I have just made it a normal transaction (which means it will error if anyone tries to de-serialize a `BlockCompleteEntry` with pruned txs).

A PR is already open to add pruned txs to monero-rs: [#138](https://github.com/monero-rs/monero-rs/pull/138)

