diff --git a/.gitignore b/.gitignore
index f10df12..64ce072 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,5 +4,6 @@ composer.lock
 phpspec.yml
 phpunit.xml
 .phpunit.result.cache
+.phpunit.cache/
 vendor/
 .idea/
diff --git a/README.md b/README.md
index 72c1024..1169624 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![Latest Version](https://img.shields.io/github/release/php-http/cakephp-adapter.svg?style=flat-square)](https://github.com/php-http/cakephp-adapter/releases)
 [![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE)
-[![Build Status](https://img.shields.io/travis/php-http/cakephp-adapter.svg?style=flat-square)](https://travis-ci.org/php-http/cakephp-adapter)
+[![CI](https://github.com/php-http/cakephp-adapter/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/php-http/cakephp-adapter/actions/workflows/ci.yml)
 [![Code Coverage](https://img.shields.io/scrutinizer/coverage/g/php-http/cakephp-adapter.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/cakephp-adapter)
 [![Quality Score](https://img.shields.io/scrutinizer/g/php-http/cakephp-adapter.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/cakephp-adapter)
 [![Minimum PHP Version](https://img.shields.io/badge/php-%3E%3D%208.1-8892BF.svg)](https://php.net/)
@@ -10,8 +10,18 @@
 
 [HTTPlug](http://httplug.io) adapter for the [CakePHP](https://cakephp.org/) HTTP library.
 
+# Deprecated
+
+The CakePHP HTTP client implements the PSR-18 `HttpClientInterface`. If your code still relies on the HTTPlug `HttpClient`, we recommend to upgrade to rely on the compatible PSR-18 `HttpClientInterface` interface directly instead.
+
+## Version Info
+
 This branch is for use with CakePHP 5.0+.
 
+- ^0.2: CakePHP 3
+- ^0.3: CakePHP 4
+- ^0.4: CakePHP 5
+
 ## Install
 
 Via Composer
@@ -20,9 +30,6 @@ Via Composer
 $ composer require php-http/cakephp-adapter
 ```
 
-## Usage
-
-
 ## Testing
 
 Start the development server using
diff --git a/composer.json b/composer.json
index 20deabf..d8d8018 100644
--- a/composer.json
+++ b/composer.json
@@ -1,4 +1,5 @@
 {
+    "abandoned": "cakephp/http",
     "name": "php-http/cakephp-adapter",
     "description": "CakePHP adapter for PHP-HTTP",
     "license": "MIT",
@@ -13,6 +14,10 @@
         {
             "name": "Joel Wurtz",
             "email": "joel.wurtz@gmail.com"
+        },
+        {
+            "name": "Mark Scherer",
+            "email": "euromark@web.de"
         }
     ],
     "require": {
@@ -22,7 +27,7 @@
         "cakephp/cakephp": "^5.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.5",
+        "phpunit/phpunit": "^10.3",
         "php-http/message-factory": "^1.0.2",
         "spryker/code-sniffer": "^0.17.15"
     },
@@ -53,12 +58,13 @@
     "prefer-stable": true,
     "config": {
         "allow-plugins": {
-            "dealerdirect/phpcodesniffer-composer-installer": true
+            "dealerdirect/phpcodesniffer-composer-installer": true,
+            "php-http/discovery": true
         }
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "0.3-dev"
+            "dev-master": "0.4-dev"
         }
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index eef2c8e..457866b 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit colors="true" bootstrap="vendor/autoload.php">
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" colors="true" bootstrap="vendor/autoload.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.3/phpunit.xsd" cacheDirectory=".phpunit.cache">
+
     <testsuites>
         <testsuite name="Guzzle 5 Adapter Test Suite">
             <directory>tests/</directory>
@@ -8,9 +9,11 @@
     <php>
         <server name="TEST_SERVER" value="http://127.0.0.1:10000/server.php"/>
     </php>
-    <filter>
-        <whitelist>
+
+    <source>
+        <include>
             <directory suffix=".php">src/</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </source>
+
 </phpunit>