Replace cursor_pagination with pagy_cursor

[crazyoptimist]

Close #148 #126
cursor_pagination is abandoned and no longer maintained.
This PR replaces it with pagy_cursor, a cursor pagination gem based on pagy.

[crazyoptimist]

@dblock this is ready for review.

[dblock]

Nice! Since this is a breaking change, let's make the version 2.0 in this PR (CHANGELOG and version.rb please).
We also mention cursor_pagination in README and possibly elsewhere.

[dangerpr-bot]

	1 Warning
⚠️	There're library changes, but not tests. That's OK as long as you're refactoring existing code.

Generated by 🚫 Danger

[crazyoptimist]

Done. Seems like tests fail due to the rate limit, which is fine.

[dblock]

Merged, thanks!

[dblock]

Looks like https://github.com/slack-ruby/slack-ruby-bot-server/actions/runs/3856495932/jobs/6572763647 failed, care to take a look?

[crazyoptimist]

Could you manually run the failed workflows again? I guess it's github.

[crazyoptimist]

I synced my master with the upstream, and ran the tests. Everything is green.

[crazyoptimist]

This might be related. Probably smaller runner image is assigned or something else during the workflow run. 9 of 10, not an issue in the code.

[dblock]

Complains about an API rate limit?

https://github.com/slack-ruby/slack-ruby-bot-server/actions/runs/3856495932/jobs/6588027991

[crazyoptimist]

Yes, it's github. So running the workflow again manually will just be fine, like when GHA servers get less load.

[dblock]

Looks like this is angular/webdriver-manager#216. We need to have reliable CI, looking at this.

[dblock]

@crazyoptimist Care to add a section to UPGRADING.md? I believe at the very least users will need to swap gems in their Gemfile.

[dblock]

Yes, it's github. So running the workflow again manually will just be fine, like when GHA servers get less load.

#159