deps: update core dependencies (#109)

Author: renovate-bot

pom.xml

@@ -63,11 +63,11 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <github.global.server>github</github.global.server>
     <site.installationModule>google-cloud-spanner-parent</site.installationModule>
-    <google.core.version>1.93.2</google.core.version>
+    <google.core.version>1.93.3</google.core.version>
     <google.api-common.version>1.9.0</google.api-common.version>
     <google.common-protos.version>1.17.0</google.common-protos.version>
     <gax.version>1.54.0</gax.version>
-    <grpc.version>1.27.2</grpc.version>
+    <grpc.version>1.28.0</grpc.version>
     <protobuf.version>3.11.4</protobuf.version>
     <junit.version>4.13</junit.version>
     <guava.version>28.2-android</guava.version>