protobuf 3.18.2 (#2262)

Author: suztomo

boms/cloud-lts-bom/pom.xml

@@ -51,7 +51,7 @@
     <!-- Layer 1: Core -->
     <guava.version>31.0.1-jre</guava.version>
     <autovalue.version>1.8.2</autovalue.version>
-    <protobuf.version>3.18.1</protobuf.version>
+    <protobuf.version>3.18.2</protobuf.version>
     <google-http-client.version>1.40.1</google-http-client.version>
     <api-common.version>2.0.5</api-common.version>
     <google-oauth-client.version>1.32.1</google-oauth-client.version>