mod+version: bump lnd to v0.18.4-beta.rc2, bump version to v0.5.0-alpha.rc2 #3573

Job	Run time
Format check	2m 32s
Docker build check	3m 48s
cross compilation	15m 53s
Compilation check	5m 21s
run itests	14m 20s
run itests postgres	22m 39s
Lint check	5m 3s
migration version check	12s
go mod check	2m 36s
RPC check	3m 22s
run LiT tests	19m 34s
sample configuration check	2m 54s
Sqlc check	2m 47s
test vector check	3m 9s
run unit tests (unit-race)	11m 56s
run unit tests (unit-cover)	7m 11s
run unit tests (unit dbbackend=postgres)	6m 13s
finish	2s
	2h 9m 32s

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