tdf#102284 Allow footnote separator thickness of 0pt

Change-Id: I7a8543836b8747f9523a844f041b143d0d18d9c5
Reviewed-on: https://gerrit.libreoffice.org/29932Reviewed-by: Yousuf Philips <philipz85@hotmail.com>
Tested-by: Yousuf Philips <philipz85@hotmail.com>

sw/uiconfig/swriter/ui/footnoteareapage.ui

@@ -16,7 +16,7 @@
     <property name="page_increment">10</property>
   </object>
   <object class="GtkAdjustment" id="adjustment3">
-    <property name="lower">0.25</property>
+    <property name="lower">0.00</property>
     <property name="upper">9</property>
     <property name="value">0.25</property>
     <property name="step_increment">1</property>