Add types parameter when calling conversations.list api.

[k-sho-boo]

This change should fix issue #63.
conversations.list api gets only public channels is default. I added parameters to get all channels.
This fix works fine on my machine.

[dornela]

@k-sho-boo I also had to add the parameter limit to fix on my machine. I believe slack api was limiting the number of channels and not bringing the private channels.
$params['limit'] = '999';

[hungri-yeti]

The commit and the additional suggestion above worked for my local install.

Note: I also needed to do run the --refresh command in the workflow.

Thank you!

[yannickglt]

Thanks for your contribution 🙂