Change concurrency class to handle more complex expressions for cancellation.

[zarthross]

Github actions allows you to set cancellation based on an expression.
Changing the cancelInProgress to a string allows me to set the
cancellation based on branch which would help my team prevent
cancellation of main branch builds in the middle of an automatic publish
leaving us in a half published state.

Example:
docs

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ !contains(github.ref, 'release/')}}

[zarthross]

Can someone look at this? I know its bin-breaking but it adds a lot of flexibility for cancellation thats very much needed.

[zarthross]

@armanbilge ?

[armanbilge]

Thanks, this is good change. With a tiny bit of nuisance we can make it compatibly, what do you think?

[zarthross]

Thanks, this is good change. With a tiny bit of nuisance we can make it compatibly, what do you think?

I liked it, I finished fleshing it out. Ready for a re-review @armanbilge

[armanbilge]

Thank you! Just need to add MiMa exceptions for the private Impl class.

[zarthross]

@armanbilge Corrected the mima warnings.

[armanbilge]

Thanks for that follow-up. Nicely done!