Lacks support for ConnectionPool >= 3.0

[s01ipsist]

https://github.com/mperham/connection_pool/blob/main/Changes.md#300

3.0.0 BREAKING CHANGES ConnectionPool and ConnectionPool::TimedStack now use keyword arguments rather than positional arguments everywhere. Expected impact is minimal as most people use the with API, which is unchanged.
Dropped support for Ruby <3.2.0

Ruby support requirements tie in with #160