Cut a release #1448

What did you do?
Tried to follow the official documentation and set --datasource.pass-file CLI flag
What did you expect to see?
Password file should have been used.
What did you see instead? Under which circumstances?
postgres_exporter: error: unknown long flag '--datasource.pass-file', try --help
Environment

• System information:

  docker

• postgres_exporter version:

  0.20.1

• Logs:

postgres_exporter: error: unknown long flag '--datasource.pass-file', try --help

The latest release is over 4 months old but the docs have been extensively updated since then. Why not cut a release?