Must one fast three days if one unknowingly ate food containing pork?

There is no sin upon a Muslim for what emanates from them unintentionally, due to Allah's saying: "Allah does not charge a soul except [with that within] its capacity. It will have [the consequence of] what it earned, and it will bear [the consequence of] what it incurred. Our Lord, do not impose blame upon us if we have forgotten or erred." And due to the Prophet's (peace be upon him) saying: "My Ummah has been forgiven for mistakes, forgetfulness, and what they are forced to do." However, if the act was intentional, then its expiation is seeking forgiveness, repentance, and regret, and not fasting for three days.