Merge pull request #5 from drkostas/dependabot/pip/protobuf-3.15.0

Bump protobuf from 3.11.3 to 3.15.0

Author: drkostas

requirements.txt

@@ -11,7 +11,7 @@ nose==1.3.7
 numpy==1.18.4
 pandas==1.0.3
 plotly==4.7.1
-protobuf==3.11.3
+protobuf==3.15.0
 py4j==0.10.7
 pyrsistent==0.16.0
 pyspark==2.4.5