Add cache on startup (#717)

* Add cache on startup

* [pre-commit.ci lite] apply automatic fixes

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: MattyTheHacker

cogs/startup.py

@@ -15,9 +15,11 @@
     GuestRoleDoesNotExistError,
     GuildDoesNotExistError,
     MemberRoleDoesNotExistError,
+    MSLMembershipError,
     RolesChannelDoesNotExistError,
 )
 from utils import TeXBotBaseCog
+from utils.msl import fetch_community_group_members_list
 
 if TYPE_CHECKING:
     from collections.abc import Sequence
@@ -109,6 +111,14 @@ async def on_ready(self) -> None:
         if not discord.utils.get(main_guild.text_channels, name="general"):
             logger.warning(GeneralChannelDoesNotExistError())
 
+        try:
+            await fetch_community_group_members_list()
+        except MSLMembershipError as msl_membership_error:
+            logger.debug(
+                "Failed to update community group member list cache on startup: %s",
+                msl_membership_error,
+            )
+
         if settings["STRIKE_PERFORMED_MANUALLY_WARNING_LOCATION"] != "DM":
             manual_moderation_warning_message_location_exists: bool = bool(
                 discord.utils.get(