[gtk/ebassi/docs-ci] ci: Add missing graphviz dependency

[Emmanuele Bassi <ebassi src gnome org>]

commit f1b349270061b185c1d437b2f31ebae05369b0a0
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Mar 30 21:08:43 2021 +0100

    ci: Add missing graphviz dependency
    
    We generate the hierarchy graph for GTK types, and in order to do so, we
    need the dot utility from graphviz in the CI image.

 .gitlab-ci.yml                    | 2 +-
 .gitlab-ci/fedora-docs.Dockerfile | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e70ea303b6..a41fae5b7f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -26,7 +26,7 @@ variables:
   MESON_TEST_TIMEOUT_MULTIPLIER: 3
   FEDORA_IMAGE: "registry.gitlab.gnome.org/gnome/gtk/fedora:v28"
   FLATPAK_IMAGE: "registry.gitlab.gnome.org/gnome/gnome-runtime-images/gnome:master"
-  DOCS_IMAGE: "registry.gitlab.gnome.org/gnome/gtk/fedora-docs:v26"
+  DOCS_IMAGE: "registry.gitlab.gnome.org/gnome/gtk/fedora-docs:v27"
 
 .only-default:
   only:
diff --git a/.gitlab-ci/fedora-docs.Dockerfile b/.gitlab-ci/fedora-docs.Dockerfile
index d9c9b44ea2..909ea59f2a 100644
--- a/.gitlab-ci/fedora-docs.Dockerfile
+++ b/.gitlab-ci/fedora-docs.Dockerfile
@@ -1,6 +1,7 @@
 FROM registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28
 
 RUN dnf -y install \
+        graphviz \
         python3-jinja2 \
         python3-markdown \
         python3-pygments \