Add plotly to requirements

Change-Id: Ib8d58d485f6e4d42b3c27bc67884748b8405c380
diff --git a/setup.py b/setup.py
index b60cbac..57c894c 100644
--- a/setup.py
+++ b/setup.py
@@ -30,6 +30,7 @@
     python_requires='>=3.6',
     install_requires=[
         'rpy2>=3.3',
+        'plotly',
         'plotly-express',
         'pandas',
         'markdown'