fix: GitHub deprecation warnings

[pau1ocampos]

Closes #43

Context

GitHub will deprecate set-output command and node12 as of 31st May 2023.
@actions/core should be upgraded for v1.10.0.
action.yml file should run on node16.
Please refer to this documentation.

Description

This pull request intends to upgrade @actions/core to v1.10.0 and update action.yml file to contemplate nodejs16 instead of nodejs12 so that this action can be compliant with new GitHub requirements.

[michaelstepner]

FYI, Github has incorporated equivalent functionality to turnstyle into the Github Actions spec using the 'concurrency' parameter. softprops/turnstyle was developed in 2020 and Github added the concurrency parameter in 2021.

The native 'concurrency' implementation has additional features beyond what's possible in turnstyle, and it is lower cost: it leaves jobs pending rather than running while they wait for a previous job to end.

[jeherve]

While the concurrency parameter is useful, I'm afraid there are still situations¹ where it isn't enough to catch potential duplicated runs. In those situations, softprops/turnstyle can still be useful.

I would consequently recommend reopening this PR, it can still be useful in avoiding deprecation warnings for those still having to rely on softprops/turnstyle

Thanks!

Footnotes

1. For reference, here is one such case. ↩