[CI] Fixes rake task for automated matrix version bumping

Author: picandocodigo

rake_tasks/automation.rake

@@ -105,8 +105,8 @@ namespace :automation do
       if file == '.buildkite/pipeline.yml'
         require 'yaml'
         yaml = YAML.safe_load(content)
-        branch = version.match(/([0-9]+\.[0-9]+)\.[0-9]+.*/)[1]
-        yaml_tests_branch = yaml['steps'][1]['env']['ES_YAML_TESTS_BRANCH']
+        branch = version.match(/([0-9]+\.[0-9]+)\.[0-9]+.*/)[1].to_s
+        yaml_tests_branch = yaml['steps'][1]['env']['ES_YAML_TESTS_BRANCH'].to_s
         unless ['main', '8.x'].include? yaml_tests_branch
           content.gsub!(yaml_tests_branch, branch)
           puts "[#{yaml_tests_branch}] -> [#{branch}] in #{file.gsub('./', '')}"