[gimp/wip/Jehan/pygtk-4-distcheck] Enable gtk doc!

[Jehan <jehanp src gnome org>]

commit 0f79869668a80c5328478a187e9d897c5fc3797d
Author: Jehan <jehan girinstud io>
Date:   Sun Aug 2 22:22:45 2020 +0200

    Enable gtk doc!

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a79cf028d4..5c7fb7ff9b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -183,6 +183,7 @@ gimp-debian/testing-autotools-distcheck:
         --prefix="${INSTALL_PREFIX}"
         --enable-debug
         --disable-python
+        --enable-gtk-doc
     - make -j "$(nproc)"
     - make distcheck
   allow_failure: true