Addition subtraction of integers and integer-arrays with Timestamp is no longer supported Instead of adding subtracting n use n obj freq

Question

I am trying to gather google trends using pytrends library, but I am getting the error in the title "Addition/subtraction of integers and integer-arrays with Timestamp is no longer supported. Instead of adding/subtracting n, use n * obj.freq".

This is my code:

timeframes = []
datelist = pd.date_range('2004-01-01', '2020-01-01', freq="AS")
date = datelist[0]
while date <= datelist[len(datelist)-1]:
    start_date = date.strftime("%Y-%m-%d")
    end_date = (date+4).strftime("%Y-%m-%d")
    timeframes.append(start_date+' '+end_date)
    date = date+3

What is it I am doing wrong?