bump pytest version (#3860)

diff --git a/setup.py b/setup.py
index a003bc8..fbc7f22 100644
--- a/setup.py
+++ b/setup.py
@@ -55,7 +55,7 @@
     setup_requirements.append("cffi>=1.7")
 
 test_requirements = [
-    "pytest>=2.9.0,!=3.2.0",
+    "pytest>=3.2.1",
     "pretend",
     "iso8601",
     "pytz",