fix: Invalid UTF-8 commit messages in JSON API responses (#37542) (#37585)

Backport #37542

Co-authored-by: Nicolas <bircni@icloud.com>

---------

Co-authored-by: Nicolas <bircni@icloud.com>

services/convert/convert.go

@@ -214,7 +214,7 @@ func ToTag(repo *repo_model.Repository, t *git.Tag) *api.Tag {
 
 	return &api.Tag{
 		Name:       t.Name,
-		Message:    strings.TrimSpace(t.Message),
+		Message:    strings.ToValidUTF8(strings.TrimSpace(t.Message), "?"), // the trim is not right, 1.27 won't trim
 		ID:         t.ID.String(),
 		Commit:     ToCommitMeta(repo, t),
 		ZipballURL: zipballURL,
@@ -728,7 +728,7 @@ func ToAnnotatedTag(ctx context.Context, repo *repo_model.Repository, t *git.Tag
 		Tag:          t.Name,
 		SHA:          t.ID.String(),
 		Object:       ToAnnotatedTagObject(repo, c),
-		Message:      t.Message,
+		Message:      strings.ToValidUTF8(t.Message, "?"),
 		URL:          repo.APIURL() + "/git/tags/" + t.ID.String(),
 		Tagger:       ToCommitUser(t.Tagger),
 		Verification: ToVerification(ctx, c),