use catfish as the search tool

tasks/desktop_apps.yaml

@@ -26,3 +26,4 @@
       - gimp-help-de
       - audacity
       - notify-osd
+      - catfish

templates/xfce4-panel.xml.j2

@@ -55,7 +55,7 @@
       <property name="show-button-type" type="int" value="2"/>
       <property name="show-icons" type="bool" value="true"/>
       <property name="button-label" type="string" value=""/>
-      <property name="search-cmd" type="string" value="gnome-search-tool"/>
+      <property name="search-cmd" type="string" value="catfish"/>
       <property name="mount-open-volumes" type="bool" value="true"/>
       <property name="show-volumes" type="bool" value="true"/>
       <property name="show-bookmarks" type="bool" value="true"/>