Add DLL Search Paths for Windows with Python 3.8+

Aims to Fix #457

Author: thealanjason

pysrc/juliacall/__init__.py

@@ -50,6 +50,22 @@ def backtrace(self):
 
 def init():
     import os
+    ## For Windows and Python 3.8+ need to add dll search paths
+    import sys
+    if os.name == "nt" and sys.hexversion >= 0x308000:
+        conda_environment_path = os.environ["CONDA_PREFIX"]
+        dll_search_paths = [
+            conda_environment_path,
+            os.path.join(conda_environment_path, "Library", "mingw-w64", "bin"),
+            os.path.join(conda_environment_path, "Library", "usr", "bin"),
+            os.path.join(conda_environment_path, "Library", "bin"),
+            os.path.join(conda_environment_path, "Scripts"),
+            os.path.join(conda_environment_path, "bin")
+        ]
+        for path in dll_search_paths:
+            if os.path.exists(path):
+                os.add_dll_directory(path)
+    
     import ctypes as c
     import sys
     import subprocess