Upgrade google.auth.version to 0.15.0. (#4743)

* Upgrade google.auth.version to 0.14.0.

* Upgrade google.auth.version to 0.14.0.

* Upgrade google.auth.version to 0.15.0.

Author: kolea2

google-cloud-clients/google-cloud-storage/pom.xml

@@ -34,7 +34,7 @@
     <dependency>
       <groupId>com.google.http-client</groupId>
       <artifactId>google-http-client-apache</artifactId>
-      <version>2.0.0</version>
+      <version>2.1.0</version>
     </dependency>
 
     <!-- Test dependencies -->

google-cloud-clients/pom.xml

@@ -157,11 +157,11 @@
     <!-- make sure to keep gax version in sync with google-cloud-bom -->
     <gax.version>1.42.0</gax.version>
     <api.common.java.version>1.7.0</api.common.java.version>
-    <google.auth.version>0.13.0</google.auth.version>
+    <google.auth.version>0.15.0</google.auth.version>
     <grpc.version>1.18.0</grpc.version>
     <!-- We are currently using the *-android version to support JDK7. -->
-    <guava.version>26.0-android</guava.version>
-    <http-client-bom.version>1.28.0</http-client-bom.version>
+    <guava.version>27.1-android</guava.version>
+    <http-client-bom.version>1.29.0</http-client-bom.version>
     <oauth-client.version>1.28.0</oauth-client.version>
     <protobuf.version>3.6.1</protobuf.version>
     <!-- make sure to keep opencensus version in sync with grpc -->