Issue #494: removes close button from the settings.

Signed-off-by: Camila San <hello@camila.codes>

src/gui/settingsdialog.ui

@@ -44,7 +44,7 @@
          <enum>Qt::Horizontal</enum>
         </property>
         <property name="standardButtons">
-         <set>QDialogButtonBox::Close</set>
+         <set>QDialogButtonBox::NoButton</set>
         </property>
        </widget>
       </item>