build: enable multiScm for releases (#836)

* build: enable multiScm for releases

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

README.md

@@ -57,20 +57,20 @@ If you are using Maven without BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.11.0')
+implementation platform('com.google.cloud:libraries-bom:26.15.0')
 
 implementation 'com.google.cloud:google-cloud-texttospeech'
 ```
 If you are using Gradle without BOM, add this to your dependencies:
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-texttospeech:2.14.0'
+implementation 'com.google.cloud:google-cloud-texttospeech:2.18.0'
 ```
 
 If you are using SBT, add this to your dependencies:
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-texttospeech" % "2.14.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-texttospeech" % "2.18.0"
 ```
 
 ## Authentication