Refactor "test_package.sh" to its original purpose, add multiples checks for packages definition

assets/package.json

@@ -18,7 +18,7 @@
         "build": "tsx ../../../bin/build_package.ts .",
         "watch": "tsx ../../../bin/build_package.ts . --watch",
         "test": "pnpm run test:unit",
-        "test:unit": "../../../bin/test_package.sh . --unit",
+        "test:unit": "../../../bin/unit_test_package.sh .",
         "check": "biome check",
         "ci": "biome ci"
     },

composer.json

@@ -17,6 +17,9 @@
             "homepage": "https://symfony.com/contributors"
         }
     ],
+    "require": {
+        "php": ">=8.1"
+    },
     "autoload": {
         "psr-4": {
             "Symfony\\UX\\Swup\\": "src/"