Drop support for Rails 3.2, 4.0, and 4.1

Because the CI fails for some unknown reason, and I don't want to spend my time today for debugging on these legacy versions

.travis.yml

@@ -25,9 +25,6 @@ before_install:
 #   - gemfiles/Gemfile-rails.5.1.x
 #   - gemfiles/Gemfile-rails.5.0.x
 #   - gemfiles/Gemfile-rails.4.2.x
-#   - gemfiles/Gemfile-rails.4.1.x
-#   - gemfiles/Gemfile-rails.4.0.x
-#   - gemfiles/Gemfile-rails.3.2.x
 
 matrix:
   include:
@@ -62,10 +59,6 @@ matrix:
       gemfile: gemfiles/Gemfile-rails.5.2.x
     - rvm: 2.3.8
       gemfile: gemfiles/Gemfile-rails.4.2.x
-    - rvm: 2.3.8
-      gemfile: gemfiles/Gemfile-rails.4.1.x
-    - rvm: 2.3.8
-      gemfile: gemfiles/Gemfile-rails.4.0.x
 
     - rvm: 2.2.10
       gemfile: gemfiles/Gemfile-rails.5.2.x
@@ -76,10 +69,6 @@ matrix:
     - rvm: 2.0.0
       gemfile: gemfiles/Gemfile-rails.4.2.x
 
-    - rvm: 2.0.0
-      gemfile: gemfiles/Gemfile-rails.3.2.x
-
-
     - rvm: ruby-head
       gemfile: gemfiles/Gemfile-rails.edge
 

README.md

@@ -1,6 +1,6 @@
 # ActiveDecorator [![Build Status](https://travis-ci.org/amatsuda/active_decorator.svg?branch=master)](https://travis-ci.org/amatsuda/active_decorator) [![Code Climate](https://codeclimate.com/github/amatsuda/active_decorator/badges/gpa.svg)](https://codeclimate.com/github/amatsuda/active_decorator)
 
-A simple and Rubyish view helper for Rails 3, Rails 4, Rails 5, and Rails 6. Keep your helpers and views Object-Oriented!
+A simple and Rubyish view helper for Rails 4, Rails 5, and Rails 6. Keep your helpers and views Object-Oriented!
 
 
 ## Features ##
@@ -17,7 +17,7 @@ A simple and Rubyish view helper for Rails 3, Rails 4, Rails 5, and Rails 6. Kee
 
 * Ruby 2.0.0, 2.1.x, 2.2.x, 2.3.x, 2.4.x, 2.5.x, 2.6.x, and 2.7 (trunk)
 
-* Rails 3.2.x, 4.0.x, 4.1.x, 4.2.x, 5.0, 5.1, 5.2, and 6.0 (edge)
+* Rails 4.2.x, 5.0, 5.1, 5.2, and 6.0 (edge)
 
 
 ## Supported ORMs ##