chore: update versions back to the latest on upstream (changed by cherrypicks)

Author: tlhquynh

README.md

@@ -19,7 +19,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file:
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>26.24.0</version>
+      <version>26.26.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -42,28 +42,28 @@ If you are using Maven without the BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner</artifactId>
-  <version>6.50.0</version>
+  <version>6.53.0</version>
 </dependency>
 
 ```
 
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.26.0')
+implementation platform('com.google.cloud:libraries-bom:26.27.0')
 
 implementation 'com.google.cloud:google-cloud-spanner'
 ```
 If you are using Gradle without BOM, add this to your dependencies:
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-spanner:6.52.1'
+implementation 'com.google.cloud:google-cloud-spanner:6.53.0'
 ```
 
 If you are using SBT, add this to your dependencies:
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.52.1"
+libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.53.0"
 ```
 <!-- {x-version-update-end} -->
 
@@ -432,7 +432,7 @@ Java is a registered trademark of Oracle and/or its affiliates.
 [kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java11.html
 [stability-image]: https://img.shields.io/badge/stability-stable-green
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-spanner.svg
-[maven-version-link]: https://central.sonatype.com/artifact/com.google.cloud/google-cloud-spanner/6.52.1
+[maven-version-link]: https://central.sonatype.com/artifact/com.google.cloud/google-cloud-spanner/6.53.0
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication
 [auth-scopes]: https://developers.google.com/identity/protocols/oauth2/scopes
 [predefined-iam-roles]: https://cloud.google.com/iam/docs/understanding-roles#predefined_roles