[gtk/macos-ci] Build harfbuzz with coretext on OS X

[Matthias Clasen <matthiasc src gnome org>]

commit 64606ab6cdb6b7386e366bd47b0c3f582c91f2a3
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jan 3 14:06:48 2021 -0500

    Build harfbuzz with coretext on OS X
    
    Pango needs it, but does not seem to do anything
    to make it happen.

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c52a26c6c9..bb985a80bd 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -159,6 +159,7 @@ macos:
             -Dintrospection=disabled
             -Dcpp_std=c++11
             -Dpixman:tests=disabled
+            -Dharfbuzz:coretext=enabled
             _build
     - ninja -C _build
   artifacts: