Bumped version of gRPC to 1.3.1

Change-Id: I7798476bd443a796e0e6a6e149ab8f66435ba4fa
diff --git a/incubator/protobuf/api/BUCK b/incubator/protobuf/api/BUCK
index 9ae1ccf..13a04d4 100644
--- a/incubator/protobuf/api/BUCK
+++ b/incubator/protobuf/api/BUCK
@@ -1,6 +1,6 @@
 COMPILE_DEPS = [
     '//lib:CORE_DEPS',
-    '//incubator/grpc-dependencies:grpc-core-repkg-1.3.0'
+    '//incubator/grpc-dependencies:grpc-core-repkg-1.3.1'
 ]
 
 TEST_DEPS = [