update Github actions so they are triggered from opening a Pull Request

[ekraffmiller]

When contributors open a PR, it would be helpful to have all the same tests run that we currently have for pushing commits

[pdurbin]

If it helps, @poikilotherm created a detailed diagram about how GitHub Actions are configured with external contributors in mind for the main "dataverse" repo:

The pull request hasn't been merged yet:

• Document container images workflows dataverse#9776

To see the diagram in context: https://dataverse-guide--9776.org.readthedocs.build/en/9776/container/auto-usage.html

[ekraffmiller]

https://dataverse-guide--9776.org.readthedocs.build/en/9776/container/auto-usage.html

@pdurbin It looks like this uses the access to secrets to control the actions triggered by external contributors. Based on our conversation at standup, I don't think we will need to do this, we'll just follow the restrictions set at the IQSS level
(https://github.com/organizations/IQSS/settings/actions).