tests: add missing sys import to event_ipc, dup_import, peer_access

The kill() calls print to sys.stderr -- these three files were missing
the import and would have raised NameError at runtime under the hang path.

Author: aryanputta

cuda_core/tests/memory_ipc/test_event_ipc.py

@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import multiprocessing as mp
+import sys
 
 import pytest
 from helpers.buffers import compare_equal_buffers, make_scratch_buffer

cuda_core/tests/memory_ipc/test_ipc_duplicate_import.py

@@ -11,6 +11,7 @@
 
 import contextlib
 import multiprocessing as mp
+import sys
 
 import pytest
 from helpers.logging import TimestampedLogger

cuda_core/tests/memory_ipc/test_peer_access.py

@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import multiprocessing as mp
+import sys
 
 import pytest
 from helpers.buffers import PatternGen