Log Message:
Update ruby-amq-protocol to 2.2.0.

## Changes between 2.1.0 and 2.2.0 (unreleased)

### Timestamps are Encoded as 64-bit Unsigned Integers

This is a potentially **breaking change**. It is recommended that
all applications that use this gem and pass date/time values in message
properties or headers are upgraded at the same time.

GitHub issue: [#64](https://github.com/ruby-amqp/amq-protocol/issues/64).

Contributed by Carl Hoerberg.