Remove unused imports in tests (GH-14518)

diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 6b8acb2..e58d092 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -3,7 +3,6 @@
 from test import support
 import subprocess
 import sys
-import platform
 import signal
 import io
 import itertools
@@ -21,17 +20,11 @@
 from test.support import FakePath
 
 try:
-    import ctypes
-except ImportError:
-    ctypes = None
-else:
-    import ctypes.util
-
-try:
     import _testcapi
 except ImportError:
     _testcapi = None
 
+
 if support.PGO:
     raise unittest.SkipTest("test is not helpful for PGO")