Merge pull request ruby-docx#146 from ruby-docx/drop-support-for-ruby-2.6

Drop support for ruby 2.6

Author: satoryu

.github/workflows/ruby.yml

@@ -17,7 +17,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: [2.6, 2.7, "3.0", 3.1, 3.2]
+        ruby: [2.7, "3.0", 3.1, 3.2]
 
     steps:
     - uses: actions/checkout@v2

docx.gemspec

@@ -11,7 +11,7 @@ Gem::Specification.new do |s|
   s.email       = ['[email protected]']
   s.homepage    = 'https://github.com/chrahunt/docx'
   s.files       = Dir['README.md', 'LICENSE.md', 'lib/**/*.rb']
-  s.required_ruby_version = '>= 2.6.0'
+  s.required_ruby_version = '>= 2.7.0'
 
   s.add_dependency 'nokogiri', '~> 1.13', '>= 1.13.0'
   s.add_dependency 'rubyzip',  '~> 2.0'