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>

Author: captain5050

tools/perf/tests/shell/lib/attr.py

@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-from __future__ import print_function
-
+import configparser
 import os
 import sys
 import glob
@@ -13,11 +12,6 @@
 import shutil
 import subprocess
 
-try:
-    import configparser
-except ImportError:
-    import ConfigParser as configparser
-
 def data_equal(a, b):
     # Allow multiple values in assignment separated by '|'
     a_list = a.split('|')