Remove unused imports in tests (GH-14518)

diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index d7e11d2..10c1e07 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -9,7 +9,7 @@
 import errno
 
 from test.support import (TESTFN, captured_stderr, check_impl_detail,
-                          check_warnings, cpython_only, gc_collect, run_unittest,
+                          check_warnings, cpython_only, gc_collect,
                           no_tracing, unlink, import_module, script_helper,
                           SuppressCrashReport)
 from test import support