Restore DCO check

[paulusmack]

Somewhere in the process of setting things up to build and test the software, we lost the DCO check (the check that each commit has a Signed-off-by: line). We need to get that back.

[Neustradamus]

@RICCIARDI-Adrien, @enaess: If you can look it ^^

[RICCIARDI-Adrien]

Hi @paulusmack, DCO check might have been lost during the repository organization migration. You can install this GitHub app https://github.com/apps/dco to enable DCO checking.

[Neustradamus]

I think that the page has been changed:

• https://github.com/probot/dco/blob/master/docs/required-statuses.md

[enaess]

I did see the DCO check flagged two of my changes recently and had a red X marked in front of it in the workflows. Seems like this has been fixed now, no?

[RICCIARDI-Adrien]

As said by @enaess, DCO check is working (see the following picture taken from a pull request), so this issue may be closed.