Log Message:
net/ruby-amq-protocol: update to 2.3.1

Update ruby-amq-protocol to 2.3.1.

## Changes between 2.3.0 and 2.3.1 (April 8th, 2020)

### Support for connection.update-secret

Used together with the `rabbitmq-auth-backend-oauth2` plugin.

### Squashed a gemspec Warning

GitHub issue: \ 
[ruby-amqp/amq-protocol#75](https://github.com/ruby-amqp/amq-protocol/issues/75).