Upgrade to dap-client 2.1.0

[jlongland]

A 2.0 version of the dap-client was released earlier this year:
https://community.canvaslms.com/t5/Canvas-Change-Log/2025-API-and-CLI-Change-Log/ta-p/626858

Primary benefit would be:

Rate Limit Awareness: The CLI now parses and respects X-RateLimit-Remaining and X-Retry-After headers returned by the CD2 API. Requests automatically delay when approaching limits, reducing transient API errors.