Remove testing against Guzzle 5

Neither it nor the HttpPlug adapter is maintained upstream anymore:
https://github.com/php-http/guzzle5-adapter#deprecated

It also does not support async requests which we want to use eventually.

Since trying to install the it in CI now causes dependency conflicts,
let’s just stop supporting it like we did with Guzzle 6.

.github/workflows/continuous-integration.yml

@@ -131,45 +131,6 @@ jobs:
       - name: "Run PHPUnit"
         run: "php vendor/bin/simple-phpunit -v"
 
-  phpunit-guzzle5:
-    name: "PHPUnit (PHP ${{ matrix.php }} and Guzzle 5)"
-    runs-on: "ubuntu-20.04"
-
-    strategy:
-      matrix:
-        php:
-          - "7.4"
-
-    steps:
-      - name: "Checkout"
-        uses: "actions/checkout@v4"
-        with:
-          fetch-depth: 2
-
-      - name: "Install PHP"
-        uses: "shivammathur/setup-php@v2"
-        with:
-          php-version: "${{ matrix.php }}"
-          coverage: "none"
-          tools: composer:v2
-          extensions: tidy
-        env:
-          COMPOSER_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
-
-      - name: "Setup adapter: Guzzle 5"
-        run: |
-          composer remove guzzlehttp/guzzle php-http/guzzle7-adapter --dev -n
-          composer require php-http/guzzle5-adapter --dev -n
-
-      - name: "Setup logs"
-        run: "mkdir -p build/logs"
-
-      - name: "Run PHPUnit"
-        run: "php vendor/bin/simple-phpunit -v"
-
   phpunit-curl:
     name: "PHPUnit (PHP ${{ matrix.php }} and cURL)"
     runs-on: "ubuntu-20.04"

README.md

@@ -59,10 +59,9 @@ Why `php-http/guzzle7-adapter`? Because Graby is decoupled from any HTTP client
 Graby is tested & should work great with:
 
 - Guzzle 7 (using `php-http/guzzle7-adapter`)
-- Guzzle 5 (using `php-http/guzzle5-adapter`)
 - cURL (using `php-http/curl-client`)
 
-Note: if you want to use Guzzle 6, use Graby 2 (support has dropped in v3 because of dependencies conflicts, which does not happen with Guzzle 5 :shrug:)
+Note: if you want to use Guzzle 5 or 6, use Graby 2 (support has dropped in v3 because of dependencies conflicts)
 
 ### Retrieve content from an url
 
@@ -193,20 +192,6 @@ $logs = $this->get('monolog.handler.graby')->getRecords();
 If you need to define a timeout, you must create the `Http\Client\HttpClient` manually,
 configure it and inject it to `Graby\Graby`.
 
-- For Guzzle 5:
-
-    ```php
-    use Graby\Graby;
-    use GuzzleHttp\Client as GuzzleClient;
-    use Http\Adapter\Guzzle5\Client as GuzzleAdapter;
-    $guzzle = new GuzzleClient([
-        'defaults' => [
-            'timeout' => 2,
-        ]
-    ]);
-    $graby = new Graby([], new GuzzleAdapter($guzzle));
-    ```
-
 - For Guzzle 7:
 
     ```php

phpstan.neon

@@ -9,9 +9,9 @@ parameters:
         - vendor/bin/.phpunit/phpunit/vendor/autoload.php
 
     ignoreErrors:
-        # because we check for some HTTP client to exist or not (Guzzle 5/6 & cURL)
+        # because we check for some HTTP client to exist or not (cURL)
         -
-            message: '#Http\\Adapter\\Guzzle5\\Client\\|Http\\Adapter\\Guzzle6\\Client\\|Http\\Client\\Curl\\Client given#'
+            message: '#Http\\Client\\Curl\\Client given#'
             path: %currentWorkingDirectory%/tests/Extractor/HttpClientTest.php
         # phpstan does not seem to recognize the class override for JSLikeHTMLElement
         -

tests/Extractor/HttpClientTest.php

@@ -266,14 +266,6 @@ public function testTimeout(): void
             $isGuzzle = true;
             $guzzle = new \GuzzleHttp\Client(['timeout' => 2]);
             $adapter = new \Http\Adapter\Guzzle7\Client($guzzle);
-        } elseif (class_exists('Http\Adapter\Guzzle6\Client')) {
-            $isGuzzle = true;
-            $guzzle = new \GuzzleHttp\Client(['timeout' => 2]);
-            $adapter = new \Http\Adapter\Guzzle6\Client($guzzle);
-        } elseif (class_exists('Http\Adapter\Guzzle5\Client')) {
-            $isGuzzle = true;
-            $guzzle = new \GuzzleHttp\Client(['defaults' => ['timeout' => 2]]);
-            $adapter = new \Http\Adapter\Guzzle5\Client($guzzle);
         } elseif (class_exists('Http\Client\Curl\Client')) {
             $isCurl = true;
             $adapter = new \Http\Client\Curl\Client(