change ruby to 5.2.1

Gemfile

@@ -1,7 +1,7 @@
 source 'https://gems.ruby-china.com'
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-ruby '2.3.7'
+ruby '2.5.1'
 
 gem 'rails', '~> 5.2.0'
 gem 'mysql2', '>= 0.4.4', '< 0.6.0'

Gemfile.lock

@@ -374,7 +374,7 @@ DEPENDENCIES
   wkhtmltopdf-binary
 
 RUBY VERSION
-   ruby 2.3.7p456
+   ruby 2.5.1p57
 
 BUNDLED WITH
    1.17.3