Groups parameter not working

[michael-zhasil-pfx]

Describe the bug
PW_GROUP or -g parameter does not work

To Reproduce
Steps to reproduce the behavior:

1. Create sources config with at leat two group for databases
2. Run instance or instances of pgwatch with PW_GROUP set to database group

Expected behavior
PGWATCH will monitor only / connect to only sources with selected group

Additional context
Pgwatch connects to all instances inside sources. While looking into source code I've found out that internal/sources/cmdopts.go contains Groups inside CmdOpts struct, but Groups are never used elsewhere

[pashagolub]

Thanks. Fixed. If you want to give it a try, I've built and pushed cybertecpostgresql/pgwatch:fix-794 tag for you.