This module proxies requests to BASE_URL/avatar/:hash to www.gravatar.com/avatar/:hash.

The purpose is to make use of Gravatar's convenient avatar service without exposing information that could be used for tracking the Plausible user. Compared to requesting the Gravatar directly from the browser, this proxy module protects the Plausible user from disclosing to Gravatar:

1. The client IP address
2. User-Agent
3. Referer header which can be used to track which site the user is visiting (i.e. plausible.io or self-hosted URL)

The downside is the added latency from the request having to go through the Plausible server, rather than contacting the local CDN server operated by Gravatar's service.