This should now be resolved in the following commit:
You might need to wait an hour or so for it to reach your local mirror, but you should then be able to update without any issues. You may want to run:
#!/bin/bash
sudo apt-get update
sudo wget https://raw.githubusercontent.com/osmc/osmc/7d1f77cf0f2cbcf67704a2caa6aaf2a59b9970ab/package/base-files-osmc/files/etc/kernel/postinst.d/apt-auto-removal-osmc -O /etc/kernel/postinst.d/apt-auto-removal-osmc
sudo apt-get dist-upgrade -y
sudo reboot
In the interim
Cheers
Sam