[bug]: run unit tests (btcd unit-cover) failure due to build tag mismatch

[Roasbeef]

Background

A test run for one of my PRs failed with:

Error: cannot read source of file "/home/runner/work/lnd/lnd/kvdb/postgres/db_conn_set.go": open /home/runner/work/lnd/lnd/kvdb/postgres/db_conn_set.go: no such file or directory
Error: Error: The process '/home/runner/work/_actions/shogo82148/actions-goveralls/v1/bin/goveralls_linux_amd64' failed with exit code 1

It looks like the postgres file it thinks should be there isn't (due to lack of a set build tag?), so even though the tests pass, it fails on sending out the coverage report.

[guggero]

Will be fixed by bumping the kvdb tag in the main go module (done by #7252). See #7251 (comment).