v0.4.0

This version introduces 2 new Prometheus metrics `coredns_blocker_allowed_requests_total` and
`coredns_blocker_blocked_requests_total`, which represent the number of DNS requests that were
allowed or blocked by the blocker plugin based on the provided blocklist. Thanks to @Thezap[1] for
contributing this feature to the plugin!

[1]: https://github.com/Thezap