chore: Add IAM v3 to gapic-generator-bom (#3778)

Discovered from
googleapis/google-cloud-java#11557 (comment)

Author: lqiu96

gapic-generator-java-bom/pom.xml

@@ -114,6 +114,11 @@
         <artifactId>proto-google-iam-v2beta</artifactId>
         <version>1.50.4-SNAPSHOT</version><!-- {x-version-update:proto-google-iam-v2beta:current} -->
       </dependency>
+      <dependency>
+        <groupId>com.google.api.grpc</groupId>
+        <artifactId>proto-google-iam-v3</artifactId>
+        <version>1.50.4-SNAPSHOT</version><!-- {x-version-update:proto-google-iam-v3:current} -->
+      </dependency>
 
       <!-- Following test deps are kept to keep them consistent with versions above -->
       <dependency>
@@ -131,6 +136,11 @@
         <artifactId>grpc-google-iam-v2beta</artifactId>
         <version>1.50.4-SNAPSHOT</version><!-- {x-version-update:grpc-google-iam-v2beta:current} -->
       </dependency>
+      <dependency>
+        <groupId>com.google.api.grpc</groupId>
+        <artifactId>grpc-google-iam-v3</artifactId>
+        <version>1.50.4-SNAPSHOT</version><!-- {x-version-update:grpc-google-iam-v3:current} -->
+      </dependency>
     </dependencies>
 
   </dependencyManagement>