deps: update protobuf (#2029)

* deps: update protobuf

* update protoc in contrib

Author: elharo

build.gradle

@@ -174,7 +174,7 @@ subprojects {
         springCloudVersion = '1.3.4.RELEASE'
         springVersion = '4.3.12.RELEASE'
         prometheusVersion = '0.6.0'
-        protobufVersion = '3.7.0'
+        protobufVersion = '3.11.4'
         zipkinReporterVersion = '2.7.14'
         jaegerReporterVersion = '0.33.1'
         opencensusProtoVersion = '0.2.0'

contrib/appengine_standard_util/build.gradle

@@ -3,7 +3,7 @@ description = 'OpenCensus AppEngine Standard Util'
 apply plugin: 'java'
 apply plugin: 'com.google.protobuf'
 
-def protocVersion = '3.6.1'
+def protocVersion = '3.11.4'
 
 buildscript {
     repositories {