chore: use stdlib uuid package

Go 1.27 ships a uuid package with the same API, dropping the direct
dependency on github.com/google/uuid.

Assisted-by: Claude:Opus 5

services/migrations/dump.go

@@ -25,8 +25,8 @@ import (
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/structs"
 
-	"github.com/google/uuid"
 	"go.yaml.in/yaml/v4"
+	"uuid"
 )
 
 var _ base.Uploader = &RepositoryDumper{}

services/migrations/gitea_uploader.go

@@ -33,7 +33,7 @@ import (
 	"gitea.dev/services/pull"
 	repo_service "gitea.dev/services/repository"
 
-	"github.com/google/uuid"
+	"uuid"
 )
 
 var _ base.Uploader = &GiteaLocalUploader{}