git push heroku masterでエラー

composer.json

{ "name": "laravel/laravel", "type": "project", "description": "The Laravel Framework.", "keywords": [ "framework", "laravel" ], "license": "MIT", "require": { "php": "^7.3|^8.0", "doctrine/dbal": "^2.6", "fideloper/proxy": "^4.0", "laravel/framework": "^6.2", "laravel/socialite": "^5.5", "laravel/tinker": "^1.0", "laravel/ui": "1.*", "socialiteproviders/twitter": "^4.1" }, "require-dev": { "facade/ignition": "^1.4", "fzaninotto/faker": "^1.4", "mockery/mockery": "^1.0", "nunomaduro/collision": "^3.0", "phpunit/phpunit": "^8.0" }, "config": { "disable-tls": false, "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" ] } }