Merge pull request #3 from dfuse-io/dependabot/pip/protobuf-3.15.0

Bump protobuf from 3.9.1 to 3.15.0

Author: Matthieu Vachon

requirements.txt

@@ -1,4 +1,4 @@
 ## The following requirements were added by pip freeze:
 grpcio-tools==1.22.0
-protobuf==3.9.1
+protobuf==3.15.0
 six==1.12.0