CI: Use shared versions GH Actions workflow

[olleolleolle]

fix #73

I took some inspiration from https://github.com/ruby/uri/blob/master/.github/workflows/test.yml and then I edited the necessary values.

(I put this as a Draft PR, since I am not sure about all the details, which engines and versions will be included.)

[eregon]

FYI, CI fails on jruby latest release, tracked as #75

[kou]

@headius Do we need both of jruby and jruby-head?

[olleolleolle]

I learned about the JRuby detail:

Yeah we had a transition period where it supported both old and new but now all released JRuby should be on the new version.

And by "the new version" headius is referring to the Joni library version.

And that should be removed.

strscan/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java

Line 105 in 8adf8b8

// Provided temporarily to bridge the gap between joni 2.1 and 2.2

In order to begin, I started a Draft PR, #76.

[headius]

I have merged #76 and master is now green on latest JRuby.

[headius]

@olleolleolle Thanks for the PR!

[olleolleolle]

In #82, kou explained the reason for the failed builds on current master (and also in this PR).

I will merge this, now. Thanks, all, for helping!