What is the ruling on a Muslim renting out an apartment he owns to a disbeliever who might drink alcohol, eat pork, or practice his disbelief therein?

There is no sin upon a Muslim who rents out his house to a Dhimmī, even if the latter uses it for drinking wine, worshipping the cross, or bringing in pigs. This is because the Muslim did not rent it out for these actions, and the sin falls upon the tenant for his actions, not upon the landlord's intent.