Tweaking the CI settings

[hibariya]

• Added an explicit require 'logger' to fix errors (like this) in some older versions of ActiveJob
• Added a bit older Ruby and ActiveJob to the test matrix
• Reduced the number of ruby x active_job combinations for too older versions

[koic]

I'm not sure from a review perspective, what version of Ruby is required? Since this affects users, it's different from just tweaking CI settings. It would be good to specify require_ruby_version in the gemspec.

[hibariya]

@koic Good question! I think no one has decided which Ruby versions this gem supports. I don't foresee a major problem with leaving it unspecified for now, but happy to change this if someone needs it. In this PR, I limited the number of combinations of Ruby and ActiveJob in the CI just because some newer ActiveJob versions require newer Ruby.

[koic]

I think the minimum Ruby version tested in CI matrix should match the required_ruby_version specified for installation. Otherwise, there could be unexpected issues between the CI environment and user runtime. It may be a good opportunity to consider aligning them now.

[hibariya]

@koic Yeah, that makes sense to me too 👍 Added: 0539ea7

[koic]

For example, since the current ruby:latest is Ruby 3.5, it is unclear whether the CI matrix for ruby:3.4 is still necessary. Anyway, I defer to your decision :-)

[hibariya]

That's a good point. Added 🙏