Pages Ruby version bumped

Fix this failure

 ruby version in .travis.yml and pages ruby version match
     Failure/Error: expect(ci_ruby_version).to eql(pages_ruby_version), msg
       2.5.3 != 2.5.8; please add a commit bumping in .travis.yml

.travis.yml

@@ -5,7 +5,7 @@ script: "./script/cibuild"
 #environment
 language: ruby
 rvm:
-  - 2.5.3
+  - 2.5.8
 
 addons:
   apt: