Bring back Ruby 2.7 support

It's EOL but the current versions of Rails are still supporting it, so
it makes sense for us to keep supporting it as well. And it doesn't give
us any extra maintenance burden as older versions have been doing.

.github/workflows/test.yml

@@ -15,6 +15,7 @@ jobs:
           - '3.2'
           - '3.1'
           - '3.0'
+          - '2.7'
         env:
           - DEVISE_ORM=active_record
           - DEVISE_ORM=mongoid

CHANGELOG.md

@@ -1,6 +1,6 @@
 ### Unreleased
 
-* Drop support to Ruby < 3.0
+* Drop support to Ruby < 2.7
 * Drop support to Rails < 6.0
 
 * enhancements

devise.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |s|
 
   s.files         = Dir["{app,config,lib}/**/*", "CHANGELOG.md", "MIT-LICENSE", "README.md"]
   s.require_paths = ["lib"]
-  s.required_ruby_version = '>= 3.0.0'
+  s.required_ruby_version = '>= 2.7.0'
 
   s.add_dependency("warden", "~> 1.2.3")
   s.add_dependency("orm_adapter", "~> 0.1")