Deduplicate YouTube videos

bot.py

@@ -59,6 +59,7 @@ class Bot(discord.Client):
             re.compile(r'^(?P<prefix>!)(?P<command>reaction)\s+(?P<q>")?(?P<query>.+)(?(q)")$'),
         )
         self.youtube = YouTube(yt_api_key, yt_channel_id)
+        self.yt_videos = []
         super().__init__()
 
     async def process_event(self, service, data):
@@ -140,6 +141,11 @@ class Bot(discord.Client):
             video = self.youtube.get_video(video_id)
         except YouTubeError as e:
             return
+        published = entry.get('published')
+        if published:
+            if [v for v, p in self.yt_videos if v == video_id and p == published]:
+                return
+            self.yt_videos.append((video_id, published))
         channel = self.get_channel(youtube_channel_id)
         if channel:
             note = ''