Upgrade connection_pool dependency

[igorkasyanchuk]

Hello,

I cannot upgrade connection_pool because of dependency. If your gemfile lock I see you have a different dependency. Maybe you need to release a minor version upgrade?

bundle update connection_pool
Fetching gem metadata from https://rubygems.org/........
Resolving dependencies...
Could not find compatible versions

Because maxmind-geoip2 >= 0.4.0 depends on connection_pool ~> 2.2
  and Gemfile depends on maxmind-geoip2 = 1.4.0,
  connection_pool ~> 2.2 is required.
So, because Gemfile depends on connection_pool ~> 3.0.2,
  version solving has failed.

[horgh]

Yes, thank you! I'll look at doing a release.

[horgh]

I've released 1.5.1 with this.