prepare v4.0.0 release

Author: pcai

CHANGELOG.md

@@ -1,6 +1,13 @@
 ### Unreleased
 
-* `HTTPI::Request#headers` and `HTTPI::Response#headers` now return `Rack::Headers` instead of `Rack::Utils::HeaderHash`
+* Add your changelog entry here
+
+### 4.0.0
+
+HTTPI is officially in maintenance mode. Our emphasis will now be on bugs, security fixes, and compatibility with the wider ecosystem. See [this issue](https://github.com/savonrb/httpi/issues/238) for details.
+
+* Adds support for rack 3.0.
+* POTENTIAL BREAKING CHANGE: `HTTPI::Request#headers` and `HTTPI::Response#headers` now return `Rack::Headers` instead of `Rack::Utils::HeaderHash`. This change is motivated by an upcoming change to rack 3.1.
 
 ### 3.0.2 (2024-02-10)
 

README.md

@@ -1,6 +1,6 @@
 # HTTPI
 
-A common interface for Ruby's HTTP libraries.
+A common interface for Ruby's HTTP libraries. This project is now in maintenance mode. For new projects, we recommend [faraday](https://github.com/lostisland/faraday).
 
 [Documentation](https://www.rubydoc.info/gems/httpi)
 
@@ -14,7 +14,7 @@ HTTPI is available through [Rubygems](https://rubygems.org/gems/httpi) and can b
 
 or add it to your Gemfile like this:
 
-    gem 'httpi', '~> 3.0.0'
+    gem 'httpi', '~> 4.0.0'
 
 ## Usage example
 

lib/httpi/version.rb

@@ -1,3 +1,3 @@
 module HTTPI
-  VERSION = '3.0.2'
+  VERSION = '4.0.0'
 end