I want to know the answer to the following question:
What ruler decreed the change to the Gregorian calendar?
All the background I'm provided with is that "In these territories, as well as in the Polish–Lithuanian Commonwealth (ruled by Anna Jagiellon) and in the Papal States, the new calendar was implemented on the date specified by the bull, with Julian Thursday, 4 October 1582, being followed by Gregorian Friday, 15 October 1582.". Is that enough to answer the question?
Answer: no