__init__.py: Windows DLL Support

Python 3.8+ on Windows: DLL search paths for dependent
shared libraries
Refs.:
- python/cpython#80266
- https://docs.python.org/3.8/library/os.html#os.add_dll_directory

Python/pywarpx/__init__.py

@@ -1,10 +1,27 @@
-# Copyright 2016-2022 The WarpX Community
+# Copyright 2016-2023 The WarpX Community
 #
 # This file is part of WarpX.
 #
 # Authors: Andrew Myers, David Grote, Lorenzo Giacomel, Axel Huebl
 # License: BSD-3-Clause-LBNL
 
+import os
+
+# Python 3.8+ on Windows: DLL search paths for dependent
+# shared libraries
+# Refs.:
+# - https://github.com/python/cpython/issues/80266
+# - https://docs.python.org/3.8/library/os.html#os.add_dll_directory
+if os.name == "nt":
+    # add anything in the current directory
+    pwd = __file__.rsplit(os.sep, 1)[0] + os.sep
+    os.add_dll_directory(pwd)
+    # add anything in PATH
+    paths = os.environ.get("PATH", "")
+    for p in paths.split(";"):
+        if os.path.exists(p):
+            os.add_dll_directory(p)
+
 from .Algo import algo
 from .Amr import amr
 from .Amrex import amrex