Interfacing a 3.3 V pulled up output to 5 V input
The 5V input might be able to still properly interpret a pull-up to 3.3V as a logic HI which would allow you to just pull up to 3.3V and connect directly.
There's also a chance that even the switch on your stepper motor, being open-drain might be able to tolerate being pulled to 5V despite it accepting 3.3V elsewhere. You would need to check the datasheet to be sure.
But if none of this works then you can do the following:
If you can live with an inverted output, you can have less circuitry.



simulate this circuit &ndash; Schematic created using CircuitLab
You can also just use a level translator or a logic buffer gate that takes a 5V supply and outputs 5V but whose logic high threshold interprets a 3.3V input as a logic HI.