[Glitch] Change the hashtag column to not display the hashtag header on pinned columns

Port 4caa9f0e69 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/hashtag_timeline/index.jsx

@@ -202,7 +202,7 @@ class HashtagTimeline extends PureComponent {
         </ColumnHeader>
 
         <StatusListContainer
-          prepend={<HashtagHeader tag={tag} disabled={!signedIn} onClick={this.handleFollow} />}
+          prepend={pinned ? null : <HashtagHeader tag={tag} disabled={!signedIn} onClick={this.handleFollow} />}
           alwaysPrepend
           trackScroll={!pinned}
           scrollKey={`hashtag_timeline-${columnId}`}