Support rendering OpenAPI spec (#36449)

Fix #20852

modules/markup/main_test.go

@@ -14,5 +14,7 @@ import (
 func TestMain(m *testing.M) {
 	setting.IsInTesting = true
 	markup.RenderBehaviorForTesting.DisableAdditionalAttributes = true
+	setting.Markdown.FileNamePatterns = []string{"*.md"}
+	markup.RefreshFileNamePatterns()
 	os.Exit(m.Run())
 }