Make ruby 2.6 the officially supported version

.rubocop.yml

@@ -8,7 +8,7 @@ require:
   - rubocop-rspec
 AllCops:
-  TargetRubyVersion: 2.5
+  TargetRubyVersion: 2.6
   TargetRailsVersion: 5.0
   Exclude:
     - 'vendor/**/*'

doc/install/installation.md

@@ -202,8 +202,8 @@ Then select 'Internet Site' and press enter to confirm the hostname.
 The Ruby interpreter is required to run GitLab.
-**Note:** The current supported Ruby (MRI) version is 2.5.x. GitLab 11.6
-  dropped support for Ruby 2.4.x.
+**Note:** The current supported Ruby (MRI) version is 2.6.x. GitLab 12.2
+  dropped support for Ruby 2.5.x.
 The use of Ruby version managers such as [RVM], [rbenv] or [chruby] with GitLab
 in production, frequently leads to hard to diagnose problems. For example,

doc/install/requirements.md

@@ -40,7 +40,7 @@ Please consider using a virtual machine to run GitLab.
 ## Ruby versions
-GitLab requires Ruby (MRI) 2.5. Support for Ruby versions below 2.5 (2.3, 2.4) will stop with GitLab 11.6.
+GitLab requires Ruby (MRI) 2.6. Support for Ruby versions below 2.6 (2.4, 2.5) will stop with GitLab 12.2.
 You will have to use the standard MRI implementation of Ruby.
 We love [JRuby](https://www.jruby.org/) and [Rubinius](https://rubinius.com) but GitLab

doc/update/upgrading_from_source.md

@@ -47,8 +47,8 @@ sudo service gitlab stop
 ### 3. Update Ruby
-NOTE: Beginning in GitLab 11.6, we only support Ruby 2.5 or higher, and dropped
-support for Ruby 2.4. Be sure to upgrade if necessary.
+NOTE: Beginning in GitLab 12.2, we only support Ruby 2.6 or higher, and dropped
+support for Ruby 2.5. Be sure to upgrade if necessary.
 You can check which version you are running with `ruby -v`.

lib/tasks/services.rake

@@ -86,7 +86,7 @@ namespace :services do
     doc_start = Time.now
     doc_path = File.join(Rails.root, 'doc', 'api', 'services.md')
-    result = ERB.new(services_template, 0, '>')
+    result = ERB.new(services_template, trim_mode: '>')
       .result(OpenStruct.new(services: services).instance_eval { binding })
     File.open(doc_path, 'w') do |f|