Update version of google-auth-java to 0.6.1 (#1888)

* Update version of google-auth-java to 0.6.1

Latest version of google-auth-java contains a fix for auth token refresh failures.

* Remove harcoded auth dependencies

Author: vkedia

google-cloud-spanner/pom.xml

@@ -152,16 +152,6 @@
       <artifactId>joda-time</artifactId>
       <version>2.9.2</version>
     </dependency>
-    <dependency>
-      <groupId>com.google.auth</groupId>
-      <artifactId>google-auth-library-credentials</artifactId>
-      <version>0.4.0</version>
-    </dependency>
-    <dependency>
-      <groupId>com.google.auth</groupId>
-      <artifactId>google-auth-library-oauth2-http</artifactId>
-      <version>0.4.0</version>
-    </dependency>
     <dependency>
       <groupId>com.google.api-client</groupId>
       <artifactId>google-api-client</artifactId>

pom.xml

@@ -90,7 +90,7 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <github.global.server>github</github.global.server>
-    <google.auth.version>0.6.0</google.auth.version>
+    <google.auth.version>0.6.1</google.auth.version>
     <grpc.version>1.0.3</grpc.version>
     <gax.version>0.8.1</gax.version>
     <generatedProto.version>0.1.5</generatedProto.version>