chore: replace gopkg.in/yaml.v3 with go.yaml.in/yaml/v3 (#8956)

- gopkg.in/yaml.v3 is archived and unmaintained
- go.yaml.in/yaml/v3 is a compatible fork under the umbrella
  of https://yaml.org/

### Tests

There is no need for more tests than already provided: it is like an upgrade to a minor version, only from a fork. I browsed the changes and there are some bug fixes. They all seem reasonably minimal. It is not one of those forks that went crazy with breaking changes 😁 And there is a non zero chance that [a bug that matters to Forgejo Actions](https://github.com/yaml/go-yaml/issues/76) is fixed there. It is rare and can wait but it did happen on Codeberg.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8956
Reviewed-by: oliverpool <oliverpool@noreply.codeberg.org>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

services/issue/template.go

@@ -16,7 +16,7 @@ import (
 	"forgejo.org/modules/log"
 	api "forgejo.org/modules/structs"
 
-	"gopkg.in/yaml.v3"
+	"go.yaml.in/yaml/v3"
 )
 
 // templateDirCandidates issue templates directory

services/migrations/dump.go

@@ -25,7 +25,7 @@ import (
 	"forgejo.org/modules/structs"
 
 	"github.com/google/uuid"
-	"gopkg.in/yaml.v3"
+	"go.yaml.in/yaml/v3"
 )
 
 var _ base.Uploader = &RepositoryDumper{}

services/migrations/restore.go

@@ -12,7 +12,7 @@ import (
 
 	base "forgejo.org/modules/migration"
 
-	"gopkg.in/yaml.v3"
+	"go.yaml.in/yaml/v3"
 )
 
 // RepositoryRestorer implements an Downloader from the local directory

services/webhook/sourcehut/builds.go

@@ -26,7 +26,7 @@ import (
 	"forgejo.org/services/webhook/shared"
 
 	"code.forgejo.org/go-chi/binding"
-	"gopkg.in/yaml.v3"
+	"go.yaml.in/yaml/v3"
 )
 
 type BuildsHandler struct{}