[dasboard] Add missing French translation

[HachemJ]

Brief summary of changes

This PR adds the French translation for the string 'No open tasks for you.'.

Testing instructions (if applicable)

1. Go to 'Admin' -> 'User accounts'
2. Click on 'Add User'
3. Create a new user (no assigned tasks) so that this message is displayed.
4. If you can’t log in, set Pending approval to No.
5. Log in to the new account.
6. Verify that the translated message appears in the top right corner.

Link(s) to related issue(s)

• Resolves [dashboard] Missing French translation #11079 (Reference the issue this fixes, if any.)

[lapadulamichael]

LGTM