Add new parameter to Client.entitlements

[DA-344]

Summary

Adds the new exclude_deleted parameter to Client.entitlements.

Related DDevs PR: discord/discord-api-docs@5f58209

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• This PR fixes an issue.
• 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, ...)