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

@@ -43,7 +43,7 @@
         "laminas/laminas-coding-standard": "~3.1.0",
         "laminas/laminas-diactoros": "^3.7",
         "phpunit/phpunit": "^11.5.42",
-        "psalm/plugin-phpunit": "^0.19.5",
+        "psalm/plugin-phpunit": "^0.20.0",
         "vimeo/psalm": "^6.13.1",
         "amphp/dns": "^1.24 || ^2.1.2",
         "amphp/socket": "^1.2.1 || ^2.3.1"