Revert "Guard import of multiprocessing"

This reverts commit bf42491.

Author: agriyakhetarpal

numcodecs/tests/test_entrypoints_backport.py

@@ -1,11 +1,7 @@
 import importlib
 import os.path
 import sys
-
-from numcodecs.tests.common import is_wasm
-
-if not is_wasm:  # pragma: no cover
-    from multiprocessing import Process
+from multiprocessing import Process
 
 import pytest