Fix whitespace in edit toolbar cancel button

The extra newline at the end of the tiddler was showing up as
whitespace in the toolbar.

core/ui/EditToolbar/cancel.tid

@@ -10,4 +10,4 @@ description: {{$:/language/Buttons/Cancel/Hint}}
 <$list filter="[<tv-config-toolbar-text>prefix[yes]]">
 <span class="tc-btn-text"><$text text={{$:/language/Buttons/Cancel/Caption}}/></span>
 </$list>
-</$button>
+</$button>