fix: adjust signrawtransactionwithkey help text

`amount` should not be required

Author: UdjinM6

src/rpc/rawtransaction.cpp

@@ -1031,7 +1031,7 @@ static RPCHelpMan signrawtransactionwithkey()
                             {"vout", RPCArg::Type::NUM, RPCArg::Optional::NO, "The output number"},
                             {"scriptPubKey", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "script key"},
                             {"redeemScript", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "(required for P2SH or P2WSH) redeem script"},
-                            {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The amount spent"},
+                            {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::OMITTED, "The amount spent"},
                         },
                     },
                 },