pl-api: fix markdown availability in gotosocial

Signed-off-by: Nicole Mikołajczyk <git@mkljczk.pl>

packages/pl-api/lib/entities/instance.ts

@@ -310,6 +310,13 @@ const instanceSchema = v.pipe(
   // Detect GoToSocial
     if (typeof data.configuration?.accounts?.allow_custom_css === 'boolean') {
       data.version = `0.0.0 (compatible; GoToSocial ${data.version})`;
+      if (!data.pleroma) {
+        data.pleroma = {
+          metadata: {
+            post_formats: data.configuration?.statuses?.supported_mime_types,
+          },
+        };
+      }
     }
 
     const apiVersions = getApiVersions(data);