[Ruby] Ruby 2.6 is now the minimum (dropping Ruby 2.5) (#20413)

* [Ruby] Ruby 2.6 is now the minimum (dropping Ruby 2.5)

* Update CircleCI to use Ruby 2.6 and drop Ruby 2.5 job

* Install python on validate_docs Ruby 2.6 image

* Maybe use fastlanetools docker image

.circleci/config.yml

@@ -254,10 +254,6 @@ workflows:
   version: 2
   build:
     jobs:
-      - tests_macos:
-          name: 'Execute tests on macOS (Xcode 11.7.0, Ruby 2.5)'
-          xcode_version: '11.7.0'
-          ruby_version: '2.5'
       - tests_macos:
           name: 'Execute tests on macOS (Xcode 11.7.0, Ruby 2.6)'
           xcode_version: '11.7.0'
@@ -286,10 +282,10 @@ workflows:
           ruby_version: '2.7'
       - validate_documentation:
           name: 'Validate Documentation'
-          ruby_version: 'circleci/ruby:2.5'
+          ruby_version: 'fastlanetools/ci:0.3.0'
       - lint_source_code:
           name: 'Lint source code'
-          ruby_version: 'circleci/ruby:2.5'
+          ruby_version: 'circleci/ruby:2.6'
       - modules_load_up_tests:
           name: 'Modules load up tests'
-          ruby_version: 'circleci/ruby:2.5'
+          ruby_version: 'circleci/ruby:2.6'

.rubocop.yml

@@ -8,7 +8,7 @@ require:
   - ./rubocop/is_string_usage.rb
 
 AllCops:
-  TargetRubyVersion: 2.5
+  TargetRubyVersion: 2.6
   NewCops: enable
   Include:
     - '**/*.rb'
@@ -24,6 +24,12 @@ AllCops:
     - '**/spec/fixtures/broken_files/broken_file.rb'
     - '**/*.provisionprofile'
 
+Lint/ErbNewArguments:
+  Enabled: false
+
+Style/SlicingWithRange:
+  Enabled: false
+
 Style/MultipleComparison:
   Enabled: false
 

fastlane.gemspec

@@ -62,7 +62,7 @@ Gem::Specification.new do |spec|
     "source_code_uri" => "https://github.com/fastlane/fastlane"
   }
 
-  spec.required_ruby_version = '>= 2.5'
+  spec.required_ruby_version = '>= 2.6'
 
   spec.files = Dir.glob("*/lib/**/*", File::FNM_DOTMATCH) + Dir["fastlane/swift/**/*"] + Dir["bin/*"] + Dir["*/README.md"] + %w(README.md LICENSE .yardopts) - Dir["fastlane/lib/fastlane/actions/device_grid/assets/*"] - Dir["fastlane/lib/fastlane/actions/docs/assets/*"]
   spec.bindir = "bin"

fastlane/lib/fastlane/plugins/template/%gem_name%.gemspec.erb

@@ -16,7 +16,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ['lib']
 
-  spec.required_ruby_version = '>= 2.5'
+  spec.required_ruby_version = '>= 2.6'
 
   # Don't add a dependency to fastlane or fastlane_re
   # since this would cause a circular dependency