Bumping LND to 0.18.1-beta

[rockstardev]

Creating this PR to prepare for updating of LND in our docker deployment.
Leaving it in draft mode so it's tested and merged as part of publishing new version.

btcpayserver/btcpayserver#6094

To test on your server connect with SSH and do:

git fetch
git checkout feat/lnd-v0.18.1-beta
btcpay-update.sh

[pavlenex]

@NicolasDorier I've tested #906, could you test this one?

[NicolasDorier]

tested

[warioishere]

@rockstardev could you bump lnd to 18.3? some important bug fixes in there see:

https://github.com/lightningnetwork/lnd/blob/0-18-3-branch/docs/release-notes/release-notes-0.18.3.md

running a routing node on btcpay below my shop and would be nice to have that because negative fees still bugs arround alot