Set version to 0.4.0

Author: github-actions[bot]

Project.toml

@@ -1,7 +1,7 @@
 name = "PythonCall"
 uuid = "6099a3de-0909-46bc-b1f4-468b9a2dfc0d"
 authors = ["Christopher Doris <github.com/cjdoris>"]
-version = "0.3.0"
+version = "0.4.0"
 
 [deps]
 Conda = "8f4d0f93-b110-5947-807f-2305c1781a2d"