deps: update core dependencies to v1.27.2 (#71)

Author: renovate-bot

pom.xml

@@ -58,7 +58,7 @@
   </licenses>
   <properties>
     <site.installationModule>google-cloud-spanner-jdbc</site.installationModule>
-    <grpc.version>1.27.1</grpc.version>
+    <grpc.version>1.27.2</grpc.version>
     <api-client.version>1.30.8</api-client.version>
     <google.core.version>1.92.5</google.core.version>
     <gax.version>1.53.1</gax.version>