Remove duplicate tags when processing remote posts

src/activitypub/handlers/create_note.rs

@@ -155,9 +155,11 @@ pub async fn handle_note(
                 if let Some(tag_name) = tag.name {
                     // Ignore invalid tags
                     if let Ok(tag_name) = normalize_tag(&tag_name) {
+                        if !tags.contains(&tag_name) {
                             tags.push(tag_name);
                         };
                     };
+                };
             } else if tag.tag_type == MENTION {
                 // Try to find profile by actor ID.
                 if let Some(href) = tag.href {