feat: Authors feature backend (and upgraded deprecated mods)

test/update_download_test.go

@@ -857,7 +857,7 @@ func newBackupTestDatabase(t *testing.T) *gorm.DB {
 			_ = sqlDB.Close()
 		}
 	})
-	if err := db.AutoMigrate(&models.Article{}); err != nil {
+	if err := db.AutoMigrate(&models.Article{}, &models.Author{}, &models.ArticleAuthor{}); err != nil {
 		t.Fatal(err)
 	}
 	for _, title := range []string{"First article", "Second article"} {