Discord.py dep update 3.1 (#2587)

* Dependency update

discord.py==1.0.1
websockets<7

[style]
black==19.3b0

[Docs]
jinja==2.10.1
urllib3==1.24.2

Changes related to breaking changes from discord.py have also been made
to match

As of this commit, help formatter is back to discord.py's default

redbot/cogs/trivia/trivia.py

@@ -444,6 +444,7 @@ class Trivia(commands.Cog):
                 break
         return "\n".join(lines)
 
+    @commands.Cog.listener()
     async def on_trivia_end(self, session: TriviaSession):
         """Event for a trivia session ending.
 
@@ -520,7 +521,7 @@ class Trivia(commands.Cog):
 
         return personal_lists + get_core_lists()
 
-    def __unload(self):
+    def cog_unload(self):
         for session in self.trivia_sessions:
             session.force_stop()