deps: update grpc dependencies to v1.29.0 (#90)

Author: renovate-bot

pom.xml

@@ -60,7 +60,7 @@
   </licenses>
   <properties>
     <site.installationModule>grafeas</site.installationModule>
-    <grpc.version>1.28.1</grpc.version>
+    <grpc.version>1.29.0</grpc.version>
     <api-client.version>1.30.9</api-client.version>
     <google.core.version>1.93.4</google.core.version>
     <gax.version>1.56.0</gax.version>