Updates Rollbax to use :logger rather than :error_logger

[stuartjohnpage]

connects to #126

note: I know this repository is no longer actively maintained based on the interaction in #122. @jgmchan, @whatyouhide, @lexmag, If you want, you can transfer the repo and hex package to revelrylabs and we can take over maintenance

Overview

We recently upgraded to Elixir 1.15 on several of our apps, and noticed that certain errors like LiveView process crashes were no longer being sent to Rollbar despite having enable_crash_reports enabled.

The problem appears to be related to the fact that Rollbax registers itself as a handler to the old :error_logger, while Elixir has been moving to :logger instead.

There's a little more background and discussion in this issue: elixir-lang/elixir#13030

What's changed

• Removal of the Rollbax.Logger module in favour of Rollbax.LoggerHandler
• Adds this handler to :logger, rather than calling :error_logger.add_report_handler
• Updates some dependencies
• Formatting changes
• Test fixes due to the changes