Update d.py to 1.6.0, aiohttp to 3.7.3, Red-Lavalink to 0.7.2 (#4728)

* Bump d.py, aiohttp, Red-Lavalink

* Remove deprecation warnings that are no longer relevant

* Max concurrency things in `Command.prepare()`

* Two random things that date back to times older than d.py 1.1...

redbot/core/commands/commands.py

@@ -485,15 +485,22 @@ class Command(CogCommandMixin, DPYCommand):
         if not await self.can_run(ctx, change_permission_state=True):
             raise CheckFailure(f"The check functions for command {self.qualified_name} failed.")
 
-        if self.cooldown_after_parsing:
-            await self._parse_arguments(ctx)
-            self._prepare_cooldowns(ctx)
-        else:
-            self._prepare_cooldowns(ctx)
-            await self._parse_arguments(ctx)
         if self._max_concurrency is not None:
             await self._max_concurrency.acquire(ctx)
-        await self.call_before_hooks(ctx)
+
+        try:
+            if self.cooldown_after_parsing:
+                await self._parse_arguments(ctx)
+                self._prepare_cooldowns(ctx)
+            else:
+                self._prepare_cooldowns(ctx)
+                await self._parse_arguments(ctx)
+
+            await self.call_before_hooks(ctx)
+        except:
+            if self._max_concurrency is not None:
+                await self._max_concurrency.release(ctx)
+            raise
 
     async def do_conversion(
         self, ctx: "Context", converter, argument: str, param: inspect.Parameter

redbot/core/commands/context.py

@@ -188,7 +188,7 @@ class Context(DPYContext):
                 else:
                     try:
                         await self.channel.delete_messages((query, resp))
-                    except (discord.HTTPException, AttributeError):
+                    except discord.HTTPException:
                         # In case the bot can't delete other users' messages,
                         # or is not a bot account
                         # or channel is a DM