fix benchmark failure with numpy 1.20+
xref https://github.com/pandas-dev/pandas/pull/38379#pullrequestreview-580260176

This will be blocking using numpy 1.20 on Github actions Checks, xref https://github.com/pandas-dev/pandas/pull/36092#issuecomment-771112784
thanks @simonjayhawkins  @meeseeksdev backport 1.2.x changed milestone, backport not needed. see https://github.com/pandas-dev/pandas/pull/39842#issuecomment-779915656