feat(automod): add mention spam type and new audit log action types

[shiftinv]

trafficstars

Summary

• Add AutoModTriggerType.mention_spam with its corresponding AutoModTriggerMetadata.mention_total_limit field
• Add missing AuditLogAction.automod_send_alert_message and .automod_timeout action types - not documented yet, but they've been around for a while (June 30th) and presumably are stable

ref: https://github.com/discord/discord-api-docs/pull/5212

Checklist

• [x] If code changes were made, then they have been tested
  • [x] I have updated the documentation to reflect the changes
  • [x] I have formatted the code properly by running task lint
  • [x] I have type-checked the code by running task pyright
• [ ] This PR fixes an issue
• [x] This PR adds something new (e.g. new method or parameters)
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [ ] This PR is not a code change (e.g. documentation, README, ...)