rpc: fix get_transactions getting v1 txes from the txpool

It would try to get their prunable hash, but v1 txes don't have one

src/rpc/core_rpc_server.cpp

@@ -583,7 +583,8 @@ namespace cryptonote
               return true;
             }
             const cryptonote::blobdata pruned = ss.str();
-            sorted_txs.push_back(std::make_tuple(h, pruned, get_transaction_prunable_hash(tx), std::string(i->tx_blob, pruned.size())));
+            const crypto::hash prunable_hash = tx.version == 1 ? crypto::null_hash : get_transaction_prunable_hash(tx);
+            sorted_txs.push_back(std::make_tuple(h, pruned, prunable_hash, std::string(i->tx_blob, pruned.size())));
             missed_txs.erase(std::find(missed_txs.begin(), missed_txs.end(), h));
             pool_tx_hashes.insert(h);
             const std::string hash_string = epee::string_tools::pod_to_hex(h);