deps: update protobuf.version to v3.11.3 (googleapis#48)

Author: renovate-bot

pom.xml

@@ -66,7 +66,7 @@
     <guava.version>28.2-android</guava.version>
     <junit.version>4.13</junit.version>
     <google.common-protos.version>1.17.0</google.common-protos.version>
-    <protobuf.version>3.11.1</protobuf.version>
+    <protobuf.version>3.11.3</protobuf.version>
     <threeten.version>1.4.1</threeten.version>
     <google.api-common.version>1.8.1</google.api-common.version>
     <spanner.version>1.47.0</spanner.version>