Installation issues for laravel 8

[theefreelancer]

This comes after typing the command composer install
Below is the error in the console or terminal; PHP Fatal error: During inheritance of ArrayAccess: Uncaught ErrorException: Return type of Illuminate\Support\Collection::offsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /opt/lampp/htdocs/OpenSource/Employee-management-system-in-laravel/vendor/laravel/framework/src/Illuminate/Support/Collection.php:1941 Stack trace: Below is my composer.json file { "name": "laravel/laravel", "type": "project", "description": "The Laravel Framework.", "keywords": [ "framework", "laravel" ], "license": "MIT", "require": { "php": "^7.1.3|^8.1", "brian2694/laravel-toastr": "^5.5", "fideloper/proxy": "^4.0", "laravel/framework": "5.8.*", "laravel/tinker": "^1.0", "maddhatter/laravel-fullcalendar": "^1.3" }, "require-dev": { "beyondcode/laravel-dump-server": "^1.0", "filp/whoops": "^2.0", "fzaninotto/faker": "^1.4", "mockery/mockery": "^1.0", "nunomaduro/collision": "^2.0", "phpunit/phpunit": "^7.5" }, "config": { "optimize-autoloader": true, "preferred-install": "dist", "sort-packages": true }, "extra": { "laravel": { "dont-discover": [] } }, "autoload": { "psr-4": { "App\": "app/" }, "classmap": [ "database/seeds", "database/factories" ] }, "autoload-dev": { "psr-4": { "Tests\": "tests/" } }, "minimum-stability": "dev", "prefer-stable": true, "scripts": { "post-autoload-dump": [ "Illuminate\Foundation\ComposerScripts::postAutoloadDump", "@php artisan package:discover --ansi" ], "post-root-package-install": [ "@php -r "file_exists('.env') || copy('.env.example', '.env');"" ], "post-create-project-cmd": [ "@php artisan key:generate --ansi" ] } } PS; PHP VERSION: 8.1 Laravel version 9