fix(git) EE-2026 git default branch (#6876)

fix(git) EE-2026 git default branch

api/http/handler/stacks/stack_update_git_redeploy.go

@@ -6,7 +6,6 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/asaskevich/govalidator"
 	"github.com/pkg/errors"
 	httperror "github.com/portainer/libhttp/error"
 	"github.com/portainer/libhttp/request"
@@ -28,9 +27,6 @@ type stackGitRedployPayload struct {
 }
 
 func (payload *stackGitRedployPayload) Validate(r *http.Request) error {
-	if govalidator.IsNull(payload.RepositoryReferenceName) {
-		payload.RepositoryReferenceName = defaultGitReferenceName
-	}
 	return nil
 }