Fix docs job

Sphinx 4.0.0 added a new dependency [0] which is causing the job to fail
at the moment.

This patch fix the problem by adding UC to the docs jobs.

[0] https://www.sphinx-doc.org/en/master/changes.html

 (LaTeX: add
tex-gyre font dependency)

Change-Id: I28019331017405c06577ada88f8e9f6d9a2afc23
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>