Update dependency psalm/plugin-phpunit to ^0.20.0

| datasource | package              | from   | to     |
| ---------- | -------------------- | ------ | ------ |
| packagist  | psalm/plugin-phpunit | 0.19.6 | 0.20.0 |


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

Author: renovate[bot]

composer.json

@@ -48,7 +48,7 @@
         "laminas/laminas-coding-standard": "^3.1.0",
         "laminas/laminas-diactoros": "^3.8.0",
         "phpunit/phpunit": "^10.5.60",
-        "psalm/plugin-phpunit": "^0.19.5",
+        "psalm/plugin-phpunit": "^0.20.0",
         "vimeo/psalm": "^6.14.2"
     },
     "suggest": {