Added support for agent header. Added all italian sport channels from DL

src/stream_link_server.py

@@ -126,6 +126,8 @@ async def stream_channel(channel_id: str, auth: bool = Depends(verify_credential
         headers['Origin'] = channel['origin']
     if 'referer' in channel:
         headers['Referer'] = channel['referer']
+    if 'agent' in channel:
+        headers['User-Agent'] = channel['agent']
 
     # Get proxy if specified
     proxy = channel.get('proxy')