Restrict marshmallow versions based on Python version

sloria · sloria · commit 4d2e2be40ffa · 2019-06-22T18:31:48.000-04:00
see marshmallow-code/marshmallow#1120 close #148
diff --git a/setup.py b/setup.py
@@ -7,7 +7,8 @@
 REQUIRES = [
     'six>=1.9.0',
     'flask>=0.10.1',
-    'marshmallow>=2.0.0',
+    'marshmallow>=2.0.0,<3.0.0rc6; python_version<"3"',
+    'marshmallow>=2.0.0; python_version>="3"',
     'webargs>=0.18.0',
     'apispec>=1.0.0',
 ]
