Handle Aurora failover

[gh-axel-czarniak]

Hello,

We made some test with your gems to handle failover on RDS Aurora database but we were not successful.

It looks like you are expecting [::PG::UnableToSend, ::PG::ConnectionBad] to detect a failover but not the one we have when this happen: PG::ReadOnlySqlTransaction: ERROR: cannot execute INSERT in a read-only transaction (ActiveRecord::StatementInvalid)

Is it expected behavior from your gem ?

Thanks for helping !