Add template for gitlab continuous integration

[cmarmo]

Dear maintainers,

this pull request adds a template file with a basic gitlab continuous integration configuration.
The generation of the template is submitted to the user answer about which CI service they would like to use.

The release step is not implemented as hosted and on premises gitlab instances may offer different mechanisms for the upload.

Thanks for your attention.

[fcollonval]

Thanks @cmarmo for the proposal. I am a bit reluctant to approve this PR as the Jupyter Developer team is not well versed in GitLab CI configuration what will make the new file unlikely to be correctly updated when needed. Moreover the current test script does not cover all the tests done in GitHub workflows.

That said, one of the reason to switch to copier is its ability to apply multiple templates to the same project. This is a perfect case for that feature as the gitlab configuration is independent of the other files.

Therefore I would advice you to create a specific template for GitLab (on GitLab?) to combine with this one following copier documentation. Then we could definitely reference that template in this repository for interested users.

[cmarmo]

Thanks @cmarmo for the proposal. I am a bit reluctant to approve this PR as the Jupyter Developer team is not well versed in GitLab CI configuration what will make the new file unlikely to be correctly updated when needed.

Thanks @fcollonval for your answer, I understand your concerns.

That said, one of the reason to switch to copier is its ability to apply multiple templates to the same project. This is a perfect case for that feature as the gitlab configuration is independent of the other files.

Thank you for the reference!

Therefore I would advice you to create a specific template for GitLab (on GitLab?) to combine with this one following copier documentation. Then we could definitely reference that template in this repository for interested users.

I would definitely do that. Thank you for your suggestion.