Converting a year and week number to the date of the Monday of the week

Question

I am trying to get the date of the Monday of the week from a week number and a year. I put together some sample code to first do what I want and then to apply it, but I get this error:

Unsupported type for timedelta days component: Series

Can someone please explain how to fix this error? Here is some sample code:

#this gives me the result that I want
import datetime
from dateutil.relativedelta import relativedelta

week = 1
year = 2021
date = datetime.date(year, 1, 4) + relativedelta(weeks=+week)
print(date)
# date = 2021-01-11

Here is where I am failing:

test = pd.DataFrame({
                    'week' : [1],
                    'year' : [2021]})
test['Date'] = datetime.date(test['year'], 1, 4) + relativedelta(weeks=+test['week'])

Result:

error: TypeError: unsupported type for timedelta days component: Series