[mutter] tests/clutter/conform: Don't run tests in parallel

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 050c21c24fad26e80336f1f82daf2577eb5e2827
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Jun 5 19:13:15 2020 +0200

    tests/clutter/conform: Don't run tests in parallel
    
    Might end up failing to acquire D-Bus names, resulting in warnings.
    Avoid that by not running the tests in parallel.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1289

 src/tests/clutter/conform/meson.build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/tests/clutter/conform/meson.build b/src/tests/clutter/conform/meson.build
index fa42a74b30..aaba31af4b 100644
--- a/src/tests/clutter/conform/meson.build
+++ b/src/tests/clutter/conform/meson.build
@@ -73,6 +73,7 @@ foreach test : clutter_conform_tests
 
   test(test, test_executable,
     suite: ['clutter', 'clutter/conform'],
-    env: test_env
+    env: test_env,
+    is_parallel: false,
   )
 endforeach