[Feature] Support non pull_request event trigger

[jprinet]

Issue

A Github workflow triggered upon PR submission (ie. with pull_request event trigger) does not have access to the repository secrets. This can be an issue if an authentication process should happen during the workflow.

An option is to trigger a second workflow with a workflow_run event which has access to secrets.

This second workflow can't however use the contributor-assistant/github-action in this context as some of the required data are only populated within a pull_request / pull_request_target context (ie. context.issue.number).

Solution

Allow to pass the pull-request number as an optional action input and use it when present

See related PR

Alternative

n/a