[FEATURE] Submit Leantime to Packagist

[rimi-itk]

Is your feature request related to a problem? Please describe.
As part of our Leantime plugins development, we use GitHub Actions to check and analyze our code.

We currently use a custom composer repository to include leantime/leantime for code analysis (cf. https://github.com/ITK-Leantime/leantime-dataexport/blob/main/composer-plugin.json):

{
    "repositories": {
        "leantime/leantime": {
            "type": "vcs",
            "url": "https://github.com/Leantime/leantime"
        }
    }
}

but this requires us to (regularly) provide a GitHub token when running composer install – and we cannot (to my/our knowledge) easily do this when running GitHub Actions.

Describe the solution you'd like
Submit https://github.com/Leantime/leantime to Packagist to make it easy to composer require leantime/leantime when needed.

Additional context
I temporarily submitted Leantime† to Packagist to test running a lot of checks on one of our plugins (cf. https://github.com/ITK-Leantime/leantime-dataexport/pull/10/checks) and everything seems to work like a charm.

† I've cleaned up and deleted Leantime from our Packagist account.