make test script compatible with python 3.8

lambda_multiprocessing/test_main.py

@@ -5,12 +5,23 @@
 from typing import Tuple, Optional
 from pathlib import Path
 import os
-from functools import cache
+import sys
+
 
 import boto3
 from moto import mock_aws
 from lambda_multiprocessing.timeout import TimeoutManager, TestTimeoutException
 
+if sys.version_info < (3, 9):
+    # functools.cache was added in 3.9
+    # define an empty decorator that doesn't do anything
+    # (our usage of the cache isn't essential)
+    def cache(func):
+        return func
+else:
+    # Import the cache function from functools for Python 3.9 and above
+    from functools import cache
+
 # add an overhead for duration when asserting the duration of child processes
 # if other processes are hogging CPU, make this bigger
 delta = 0.1
@@ -39,7 +50,7 @@ def return_with_sleep(x, delay=0.3):
 
 def _raise(ex: Optional[Exception]):
     if ex:
-        raise exfrom .timeout
+        raise ex
 
 class ExceptionA(Exception):
     pass