deps: update core dependencies (#241)

Author: renovate-bot

pom.xml

@@ -155,10 +155,10 @@
     <google.api-common.version>1.9.2</google.api-common.version>
     <google.common-protos.version>1.18.0</google.common-protos.version>
     <google.iam.version>0.13.0</google.iam.version>
-    <google.auth.version>0.20.0</google.auth.version>
+    <google.auth.version>0.21.0</google.auth.version>
     <google.api.version>1.30.9</google.api.version>
     <google.http.version>1.35.0</google.http.version>
-    <grpc.version>1.30.0</grpc.version>
+    <grpc.version>1.30.2</grpc.version>
     <protobuf.version>3.12.2</protobuf.version>
     <opencensus.version>0.24.0</opencensus.version>
     <annotations-api.version>1.3.2</annotations-api.version>