Log Message:
todoman: update to 3.6.0.

v3.6.0
------
* Allow passing a custom configuration file with the ``--config/-c`` option.
* Cached list metadata is now invalidated when it has changed on-disk.
* Support for click < 6.0 has been dropped (it wasn't actually working
  perfectly any more anyway). Click 7.x is the only currently supported
  version.
* ``click-repl`` is now listed as an optional dependency. It is required for
  the ``todo repl`` command.
* Add the ``default_priority`` config setting.