Remove support for EOL Ruby 2.6/2.7, Rails 5.2/6.0

[bkeepers]

I propose we drop support for EOL Ruby and Rails versions. ~~Any reservations about doing this now before the upcoming 1.1 release?~~ We will wait until the 2.0 release.

EOL dates: Ruby 2.6 - 31 Mar 2022 - 20 months ago Rails 5.2 - 01 Jun 2022 - 18 months ago Ruby 2.7 - 31 Mar 2023 - 8 months ago Rails 6.0 - 01 Jun 2023 - 6 months ago

[dpep]

I'm a big fan of cleanups and simplifications! Ruby 2.6 and Rails 5 can definitely go. I'm more on the fence about Ruby 2.7

can we add the constraint to the gemspec (gem.required_ruby_version = ">= 3") and do a major version bump to communicate the breaking change?

[bkeepers]

can we add the constraint to the gemspec (gem.required_ruby_version = ">= 3") and do a major version bump to communicate the breaking change?

Yes, good suggestion. I think I'll let this sit for now because we do still have some Flipper Cloud customers using Ruby 2.7. I added framework stats in #780 so we can see if anyone is using old Rails versions, and that will go out in 1.1 hopefully this week.