perf test: Address attr.py mypy error

ConfigParser existed in python2 but not in python3 causing mypy to
fail.
Whilst removing a python2 workaround remove reference to __future__.

Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250311213628.569562-6-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>