replaced newsletter_publication with newsletterPublication

src/types.nim

@@ -128,7 +128,7 @@ type
     videoDirectMessage = "video_direct_message"
     imageDirectMessage = "image_direct_message"
     audiospace = "audiospace"
-    newsletter_publication = "newsletter_publication"
+    newsletterPublication = "newsletter_publication"
     unknown
     
   Card* = object