deps: update dependency com.google.protobuf:protobuf-bom to v3.21.8 (#481)

Author: renovate-bot

pom.xml

@@ -70,7 +70,7 @@
       <dependency>
         <groupId>com.google.protobuf</groupId>
         <artifactId>protobuf-bom</artifactId>
-        <version>3.21.7</version>
+        <version>3.21.8</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>