deps: update dependency io.grpc:grpc-bom to v1.29.0

Author: renovate-bot

pom.xml

@@ -156,7 +156,7 @@
  <google.api-common.version>1.9.0</google.api-common.version>
  <google.common-protos.version>1.18.0</google.common-protos.version>
  <gax.version>1.56.0</gax.version>
- <grpc.version>1.28.1</grpc.version>
+ <grpc.version>1.29.0</grpc.version>
  <protobuf.version>3.11.4</protobuf.version>
  <junit.version>4.13</junit.version>
  <guava.version>29.0-android</guava.version>