chore: autoloader pour les tests

composer.json

@@ -17,9 +17,15 @@
         "dealerdirect/phpcodesniffer-composer-installer": "^1.0",
         "phpcompatibility/php-compatibility": "dev-develop",
         "phpstan/phpstan": "^1.10",
+        "phpunit/phpunit": "^10.1",
         "rector/rector": "^0.15.23",
         "spip/coding-standards": "^1.3"
     },
+    "autoload-dev": {
+        "psr-4": {
+            "Spip\\Test\\Images\\": "tests/"
+        }
+    },
     "config": {
         "allow-plugins": {
             "dealerdirect/phpcodesniffer-composer-installer": true