tweaks: Update setting defaults.

`video_grace_period` now 90 seconds.
`task_limit` now 99.
`rent_member_limit` now 24.

Also updated `Integer` default `_min` and `_max` to match DB values.

bot/modules/todo/admin.py

@@ -16,7 +16,7 @@ class task_limit(settings.Integer, GuildSetting):
     display_name = "task_limit"
     desc = "Maximum number of tasks each user may have."
 
-    _default = 30
+    _default = 99
 
     long_desc = (
         "Maximum number of tasks each user may have in the todo system."