You said you were "told it was bought by a bank at auction"
Since you are renting the place, did you receive any type of notice posted on your door? Usually, in the case of foreclosure, the bank will post something to let the residents know if they need to vacate.
And....what type of lease do you have on your place? If you have a month-to-month, and depending on the buyer, you may want to consider locating a replacement rental. But if you have a longer lease in writing, the buyer may need to honor that lease, unless they are going to be owner-residents in which case they will need to give you notice to vacate. Depending on how long you've resided there, it could be 30 - 60 days.