[gtk-doc] ci: add python3-coverage dependency

[Stefan Sauer <stefkost src gnome org>]

commit f7917b4367e9012ef0ba29d246340e623ce23353
Author: Stefan Sauer <ensonic users sf net>
Date:   Fri Dec 14 21:19:41 2018 +0100

    ci: add python3-coverage dependency

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9704337..3c1fa7b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,7 +6,7 @@ before_script:
                 autoconf automake bc build-essential libtool make meson pkg-config
                 dblatex docbook docbook-xml docbook-xsl libxml2-utils xsltproc
                 libglib2.0-dev
-                python3 python3-dev python3-lxml python3-parameterized
+                python3 python3-coverage python3-dev python3-lxml python3-parameterized
                 python3-pip python3-pygments python3-setuptools python3-unittest2
   - pip3 install anytree
   - export LANG=C.UTF-8