0.31.0 compatibilty

[sam0x17]

This is the first error that comes up, though there are likely others:

In lib/clear/src/clear/sql/connection_pool.cr:2:35

 2 | @@connections = {} of String => Channel::Buffered(DB::Database)
                                     ^----------------
Error: undefined constant Channel::Buffered

[anykeyh]

You can use branch: v0.7.2 in your shard to make it works temporarily.

Note than there's still a bug with pg array described here

[anykeyh]

Closed by #143