deps: update dependency com.google.auth:google-auth-library-bom to v0.20.0 (#135)

Author: renovate-bot

pom.xml

@@ -156,7 +156,7 @@
     <google.api-common.version>1.8.1</google.api-common.version>
     <google.common-protos.version>1.17.0</google.common-protos.version>
     <google.iam.version>0.13.0</google.iam.version>
-    <google.auth.version>0.19.0</google.auth.version>
+    <google.auth.version>0.20.0</google.auth.version>
     <google.api.version>1.30.7</google.api.version>
     <google.http.version>1.34.0</google.http.version>
     <grpc.version>1.26.0</grpc.version>