Update convert.xml

Author: dianichj

tools/image_processing/graphicsmagick/convert.xml

@@ -29,7 +29,7 @@
 ]]>
     </command>
     <inputs>
-        <param format="jpg,png,bmp,gif,svg,eps,tiff,xcf" name="input" type="data" label="Image to convert" />
+        <param format="jpg,png,bmp,gif,svg,eps,tiff" name="input" type="data" label="Image to convert" />
         <param name="transformations" multiple="true" type="select" display="checkboxes" label="Transformations">
             <option value="-flip">flip vertically</option>
             <option value="-flop">flip horizontally</option>