Bumps the fee of an opt-in-RBF transaction, returning the new transaction as a PSBT instead of broadcasting.
txidstringREQUIREDoptionsobjectoptionalcurl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"psbtbumpfee","params":["txid"]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/{
"psbt": "cHNidP8BA...",
"origfee": 0.00001410,
"fee": 0.00003520,
"errors": []
}