Update phpstan/phpstan requirement from ^1.6 to ^1.7

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/1.7.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.6.0...1.7.8)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -45,7 +45,7 @@
         "laminas/laminas-diactoros": "^2.9",
         "nyholm/psr7": "^1.5",
         "php-http/psr7-integration-tests": "dev-master",
-        "phpstan/phpstan": "^1.6",
+        "phpstan/phpstan": "^1.7",
         "phpunit/phpunit": "^9.5",
         "squizlabs/php_codesniffer": "^3.6"
     },