Allow crypton-connection 0.4.

[alaendle]

Something for a new v0.23 of amqp.

[hreinhardt]

Thanks. I'm a little rusty on the package versioning policies, but couldn't it be 0.22.3?

[alaendle]

@hreinhardt Since I lifted the lower bound of crypton-connection I believe this is a "transparent" breaking change - so my interpretation of the PVP is that with this change in place amqp should move to 0.23. Or to put it the other way around, a minor version update (0.22.3) would indicate that existing code (maybe targeting amqp 0.22.2 and crypton-connection 0.3) could be build without changes - which is not the case.

[hreinhardt]

OK, I decided to play it safe and pick 0.23.0. 😄