Use Composer 2.8 in CI for now

Author: axlon

.github/workflows/tests.yml

@@ -110,7 +110,7 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
-          tools: composer:v2
+          tools: composer:2.8
 
       - name: Install dependencies
         run: |

composer.json

@@ -24,7 +24,7 @@
         "illuminate/validation": "^5.5 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 || ^11.0 || ^12.0"
     },
     "require-dev": {
-        "guzzlehttp/guzzle": "^7.8",
+        "guzzlehttp/guzzle": "^6.3 || ^7.8",
         "phpunit/phpunit": "^8.5 || ^9.6 || ^10.5",
         "symfony/var-exporter": "^4.0 || ^5.0 || ^6.0 || ^7.0"
     },