Update dependency psalm/plugin-phpunit to ^0.20.0

| datasource | package              | from   | to     |
| ---------- | -------------------- | ------ | ------ |
| packagist  | psalm/plugin-phpunit | 0.19.5 | 0.20.0 |


Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

composer.json

@@ -46,7 +46,7 @@
         "laminas/laminas-coding-standard": "^3.0",
         "laminas/laminas-test": "^4.10",
         "phpunit/phpunit": "^11.3.0",
-        "psalm/plugin-phpunit": "^0.19.0",
+        "psalm/plugin-phpunit": "^0.20.0",
         "vimeo/psalm": "^6.13.1"
     },
     "scripts": {