Add correct user to ssh.app group so multi-instance works.

[ndarilek]

Problem

• Description of why you made this PR

Solution

• And how do you fix that problem

PR Status

• [x] Code finished and ready to be reviewed/tested
• [x] The fix/enhancement were manually tested (if applicable)

Automatic tests

Automatic tests can be triggered on https://ci-apps-dev.yunohost.org/ after creating the PR, by commenting "!testme", "!gogogadgetoci" or "By the power of systemd, I invoke The Great App CI to test this Pull Request!". (N.B. : for this to work you need to be a member of the Yunohost-Apps organization)

[ndarilek]

!testme

[ndarilek]

This should be ready to merge--not sure what if anything I need to do on my end. Thanks!

[Josue-T]

!testme

[yunohost-bot]

:v:

[Josue-T]

!testme

[yunohost-bot]

Alrighty!

[ndarilek]

How would I go about getting this merged?

Thanks.