Adding project through Github URL does not support multi-repo

[patrickdb]

Describe the bug
Most of our long term projects are managed in a github organization. This is the entry page of the project with links to multi repos. Adding a new project does not accept these type of github (f.e. https://github.com/LOUPE-PIT) projects. It is not an option to add a project per repo, because these repos form one project.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'add project'
2. Add 'https://github.com/LOUPE-PIT'

Expected behavior
Accept links to Github organizations

Screenshots
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Production URL
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Additional context
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