CLN offers sub-1sat-per-vbyte fee on regtest

[rustyrussell]

v23.08rc1-38-g5f8b77480:

$ l1-cli close 445x1x1 
# Sending closing fee offer 183sat, with range 0sat-183sat
# Received closing fee offer 183sat, with range 0sat-1000000sat
{
   "tx": "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",
   "txid": "216ed9adf8df623770e219f52b31350de60cd1b236d6f043664d9eb5bc462ad4",
   "type": "mutual"
}
rusty@rusty-Framework:~/devel/cvs/lightning (master)$ bt-cli getrawmempool
[
]

Logs show:

2023-08-11T02:20:13.947Z DEBUG   plugin-bcli: sendrawtx exit 26 (bitcoin-cli -regtest -datadir=/home/rusty/.bitcoin sendrawtransaction 0200000000010153ce29f4df20875492760ec51092d01ade3da99ffd72c3ff47b02e8f78a5845a0100000000ffffffff02b882010000000000225120847b3d31b036c0b4fad77fd41805f375f4fc9507d52f2a19d858b43975a633b0d1be0d000000000022512017912fd7fc767d03e02461bd932556d78291ea226db5efec84d84a5c753a650a0400473044022005b184a595ec0b650dffb3168d003b13ae0d98d456d879ec7fac7012f3dbad6202202f5a9620a59fb3cb9269be3b2a941f18fe1b7e3037c259125c56d3ec86c8e91a014730440220559f1c2a578e35a975466bb6f2319d313cd79070add77c51b6f6aeb25f7eae9802204749e84e7f8a777c66896a38588f6046a28653a493c34c79a0080580a0f389ec01475221024ff290301210ddffa14db591eb629d864bb4b4583586f5bffaaebc4ca8d5edef2102e0de3f54ca6cf38cb527b326242bf418a4a0a50485c97999074e69e127216fd052ae00000000) error code: -26\nerror message:\nmin relay fee not met, 183 < 192

Indeed, tx weight is 192!