Hello,

Thank you for submitting this pull request.
This update will be very useful for me.

However, I noticed an issue regarding compatibility with classical devices that do not support CAN FD.
In the latest release, a device can be initialized as follows:

bus = can.interface.Bus(interface="slcan", channel="COM9", bitrate=500000)

When using your branch, the initialization fails with the following exception:

Invalid data bitrate, choose one of 2000000, 5000000.

In my opinion, the initialization should still work to support classical slcan devices.

By the way, I tested the CAN FD capability with a 500k/2Mbps bus.
I had no issue with sending/receiving on a Windows PC.

Thank you.