Decode the Hex registry protobuf format, filter releases by fetching
timestamps from the Hex HTTP API (hex.pm/api/packages/{name}), and
re-encode without the original signature.
The protobuf handling uses protowire for low-level encoding/decoding
of the Signed wrapper, Package, and Release messages. Timestamps come
from the inserted_at field in the JSON API response.
Since the proxy re-encodes the payload without the original signature,
users need to disable registry signature verification.