Rotate is required when it shouldn't be

[svenove]

Describe the bug According to this, the "rotate"-setting is not required: https://github.com/jonasniesner/open_epaper_link_homeassistant/blob/main/custom_components/open_epaper_link/services.yaml#L68

But, if using "drawcustom" without "rotate" causes an error.

To Reproduce Steps to reproduce the behavior:

1. Create an automation for "drawcustom" without adding "rotate".
2. Run the automation and you get this error: not all arguments converted during string formatting

Expected behavior It should just default to "rotation: 0" if not specified.