Add maximum date in due date input field

Author: lulunac27a

templates/index.html

@@ -38,6 +38,7 @@ <h1>Endless Task List App using Flask</h1>
           id="due_date"
           name="due_date"
           min="{{ today }}"
+          max="9999-12-31"
           required
         /><br />
         <input type="submit" value="Add Task" />