fix stubs version check (Netflix#1748)

Author: madhur-ob

.gitignore

@@ -29,3 +29,4 @@ main.js.map
 # Pycharm
 .idea
 
+stubs/version.py

stubs/MANIFEST.in

@@ -1,3 +1,4 @@
 include metaflow-stubs/**/*.pyi
 include metaflow-stubs/py.typed
 include metaflow-stubs/generated_for.txt
+include version.py

stubs/setup.py

@@ -1,6 +1,14 @@
+import os
+import shutil
 from setuptools import setup
 
-with open("../metaflow/version.py", mode="r") as f:
+source_file = "../metaflow/version.py"
+destination_file = "./version.py"
+
+if not os.path.exists(destination_file):
+    shutil.copy(source_file, destination_file)
+
+with open(destination_file, mode="r") as f:
     version = f.read().splitlines()[0].split("=")[1].strip(" \"'")
 
 setup(