feat(ops/gerrit-webhook-to-irccat): notify when CLs are undrafted

- Extend the notification template to handle `wip-state-changed` events where a change is undrafted (i.e., `.Change.Wip` is false or not present).
- Add test cases for undrafting (should notify) and re-drafting (should not notify).
- Ensure correct handling of `.Changer.Username` for undraft notifications.
- Update Go module dependencies for test coverage. (`go mod tidy`)

This allows the IRC bot to notify when a change is moved out of
WIP/draft state, improving visibility for ready-for-review CLs.

Fixes #167.

Change-Id: I6a6a69642369726c3bd9f523ae025c34dba8c4aa
Reviewed-on: https://cl.snix.dev/c/snix/+/30641
Reviewed-by: Oleksandr Knyshuk <olk@disr.it>
Tested-by: besadii
Reviewed-by: Florian Klink <flokli@flokli.de>

ops/gerrit-webhook-to-irccat/go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/andygrunwald/go-gerrit v1.0.0
 	github.com/coreos/go-systemd/v22 v22.5.0
 	github.com/samber/slog-http v1.6.0
+	github.com/stretchr/testify v1.10.0
 	golang.org/x/sync v0.13.0
 )
 
@@ -13,7 +14,6 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/stretchr/testify v1.10.0 // indirect
 	go.opentelemetry.io/otel v1.29.0 // indirect
 	go.opentelemetry.io/otel/trace v1.29.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect