Add version parameter to Perses-CI + add test

[AntoineThebaud]

Proposed solution to come around a misleading situation today: e.g with such piece of config in perses/perses repo:

- uses: perses/[email protected]
- uses: ./.github/perses-ci/actions/setup_environment

Since ref in Perses-CI here was hardcoded to v0.5.2, then this version was the actual one used to retrieve the actions code, not v0.6.0.

So with this change the same config would be instead:

- uses: perses/github-actions
  with:
    version: v0.6.0
- uses: ./.github/perses-ci/actions/setup_environment

And you'd really get the v0.6.0 version of perses/github-actions's actions this time.

NB: actually, by the book, to be resilient to breaking changes made to Perses-CI we should still provide a version number in the uses clause, so maybe here:

- uses: perses/[email protected]
  with:
    version: v0.6.0

Feels redundant but the 2 versions are actually used for different things 😅

[AntoineThebaud]

In the end I prefer to keep the "hardcoded" version approach that avoids adding a version parameter. We just have to think about updating the version in the main action.yaml before releasing but I'll add a RELEASE.md doc to remind about that