deps: update bigtable-metrics-api version (#4193)

The new version bigtable-metrics-api makes metrics-core an optional dependency

Change-Id: Ic9e0b312b47ed67c9c52f5088fc9ffb93f13e61b

Author: igorbernstein2

pom.xml

@@ -58,7 +58,7 @@ limitations under the License.
     <!-- core dependency versions -->
     <bigtable.version>2.28.0</bigtable.version>
     <google-cloud-bigtable-emulator.version>0.165.0</google-cloud-bigtable-emulator.version>
-    <bigtable-client-core.version>1.28.0</bigtable-client-core.version>
+    <bigtable-client-core.version>1.29.2</bigtable-client-core.version>
     <grpc-conscrypt.version>2.5.2</grpc-conscrypt.version>
     <!--  keeping at this version to align with hbase-->
     <slf4j.version>1.7.25</slf4j.version>