[gtksourceview] tests: add margin to test-widget

[Christian Hergert <chergert src gnome org>]

commit a5966bcdf26d2f3c82b4a3b12cabd6471b319c66
Author: Christian Hergert <chergert redhat com>
Date:   Sun Dec 26 11:36:06 2021 -0800

    tests: add margin to test-widget
    
    This helps catch various issues that might be margin related.

 tests/test-widget.ui | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/tests/test-widget.ui b/tests/test-widget.ui
index a86898c2..1185a465 100644
--- a/tests/test-widget.ui
+++ b/tests/test-widget.ui
@@ -464,6 +464,10 @@
                 <property name="hexpand">True</property>
                 <property name="vexpand">True</property>
                 <property name="monospace">True</property>
+                <property name="left-margin">12</property>
+                <property name="top-margin">12</property>
+                <property name="bottom-margin">12</property>
+                <property name="right-margin">12</property>
               </object>
             </child>
           </object>