Update guzzlehttp/guzzle requirement from ^6.3 to ^6.3 || ^7.0

Updates the requirements on [guzzlehttp/guzzle](https://github.com/guzzle/guzzle) to permit the latest version.
- [Release notes](https://github.com/guzzle/guzzle/releases)
- [Changelog](https://github.com/guzzle/guzzle/blob/master/CHANGELOG.md)
- [Commits](guzzle/guzzle@6.3.0...7.0.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

composer.json

@@ -3,7 +3,7 @@
     "description": "Aliyun DrirectMail Transport for Laravel Application.",
     "type": "library",
     "require": {
-        "guzzlehttp/guzzle": "^6.3",
+        "guzzlehttp/guzzle": "^6.3 || ^7.0",
         "laravel/framework": "^7.0",
         "swiftmailer/swiftmailer": "^6.1"
     },