v2.125.0

This release features a change to the proxy's cache eviction strategy to
ensure that clients (and their load balancers) are reused by new
outbound connections. This can dramatically reduce memory consumption,
especially for busy HTTP/1.1 clients.

Also, the proxy's HTTP detection scheme has been made more robust.
Previously, the proxy would perform a only single read to determine
whether a TCP stream was HTTP, which could lead to false positives. Now,
the proxy reads until at least the first newline, which is what the HTTP
parser actually needs to make a proper determination. With this, the
default dispatch timeouts have been increased to 5s to accomodate
connection pools that may not issue an immediate request.

Furthermore, this release includes an upgrade to Tokio v0.3 and its
associated ecosystem.