deps: update dependency com.google.protobuf:protobuf-bom to v3.18.0 (#224)

Author: renovate-bot

pom.xml

@@ -63,7 +63,7 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <github.global.server>github</github.global.server>
     <site.installationModule>google-iam-parent</site.installationModule>
-    <protobuf.version>3.17.3</protobuf.version>
+    <protobuf.version>3.18.0</protobuf.version>
     <junit.version>4.13.2</junit.version>
     <grpc.version>1.38.1</grpc.version>
     <guava.version>30.1-android</guava.version>