Update dependency vimeo/psalm to v6

Author: renovate[bot]

composer.json

@@ -40,7 +40,7 @@
         "phpunit/phpunit": "^8.5 || ^9.2",
         "scrutinizer/ocular": "^1.6",
         "unleashedtech/php-coding-standard": "^2.7 || ^3.0",
-        "vimeo/psalm": "^4.22 || ^5.0"
+        "vimeo/psalm": "^4.22 || ^5.0 || ^6.0"
     },
     "bin": ["bin/html-to-markdown"],
     "scripts": {