Merge pull request #5959 from royalharsh/master

DocFixit: Add instructions to install protobuf3 in python readme files
diff --git a/requirements.txt b/requirements.txt
index e3208e6..0ec0e75 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,8 @@
 # GRPC Python setup requirements
+coverage>=4.0
+cython>=0.23
 enum34>=1.0.4
 futures>=2.2.0
-cython>=0.23
-coverage>=4.0
+protobuf>=3.0.0a3
 six>=1.10
-wheel>=0.29
+wheel>=0.29
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