Run `meson test` on GitLab CI

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>
1 job for master in 38 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #7856
test

00:00:38

 
Name Stage Failure
failed
test Test
1/1 Resolve unknown current user            FAIL     0.04 s (exit status 1)

OK: 0
FAIL: 1
SKIP: 0
TIMEOUT: 0

Full log written to /builds/em/libnss-unknown/_build/meson-logs/testlog.txt
ERROR: Job failed: exit code 1