README.md in google-cloud-text_to_speech-v1beta1-0.4.0 vs README.md in google-cloud-text_to_speech-v1beta1-0.5.0

@@ -69,14 +69,14 @@
 end
 ```
 
 ## Supported Ruby Versions
 
-This library is supported on Ruby 2.4+.
+This library is supported on Ruby 2.5+.
 
 Google provides official support for Ruby versions that are actively supported
 by Ruby Core—that is, Ruby versions that are either in normal maintenance or
-in security maintenance, and not end of life. Currently, this means Ruby 2.4
+in security maintenance, and not end of life. Currently, this means Ruby 2.5
 and later. Older versions of Ruby _may_ still work, but are unsupported and not
 recommended. See https://www.ruby-lang.org/en/downloads/branches/ for details
 about the Ruby support schedule.
 
 ## Which client should I use?