Make some pool variables public

Make PostgresConnectionWrapper Sendable

Sendable conformance for the connection() callback

Dependency updates

A bit of Sendable work (WIP)

Improved connection id management

Make cannotConnectNow a non-fatal error

Added connectionRetryInterval to the configuration

Merge pull request #10 from Outdooractive/9_batch_id

#9: Add a batchId to connections

Merge pull request #8 from Outdooractive/5_pool_errors

#5: More tests, added 'closeIdleConnections()', added a description to PoolInfo