Require ryp2 >= 3.3

Change-Id: Idaeda8de362fa6844a969351b7b2d3aa66c5a2b1
diff --git a/setup.py b/setup.py
index d7a8332..2f7c9c1 100644
--- a/setup.py
+++ b/setup.py
@@ -23,7 +23,7 @@
     tests_require=['nose'],
     python_requires='>=3.6',
     install_requires=[
-        'rpy2',
+        'rpy2>=3.3',
         'plotly-express',
         'pandas',
         'markdown'