Modernize PHP and Symfony version requirements; add Symfony 8 CI support

- Drop PHP <8.3 and Symfony <7.4 (both EOL), require PHP ^8.3 and symfony/config ^7.4
- Require behat ^3.31 (first version with PHP 8 attribute and PHP config support)
- Upgrade phpspec to ^8.0 (supports PHP 8.5)
- Add symfony/browser-kit and symfony/http-client to dev deps; switch from deprecated goutte driver to browserkit_http
- Update CI matrix: PHP 8.3/8.4/8.5 × Symfony 7.4 + PHP 8.4/8.5 × Symfony 8.0/8.1
- Add Symfony 8+ CI step: override behat to 4.x-dev as 3.31.0
- Restrict push trigger to master branch only (no duplicate runs on PRs)
- Add behat.dist.php for behat 4.x compatibility (PHP config format)
- Update behat.yml.dist to use FQCN extension name (works in both behat 3.x and 4.x)
- Add lock-symfony-version.sh script for pinning Symfony in CI

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

composer.json

@@ -21,16 +21,17 @@
     ],
     "homepage": "https://github.com/FriendsOfBehat/MinkExtension#readme",
     "require": {
-        "php": "^7.4 || ^8",
-        "behat/behat": "^3.0.5",
+        "php": "^8.3",
+        "behat/behat": "^3.31",
         "behat/mink": "^1.5",
-        "symfony/config": "^4.4 || ^5.0 || ^6.0 || ^7.0",
-        "symfony/deprecation-contracts": "^1.0 || ^2.0 || ^3.0"
+        "symfony/config": "^7.4",
+        "symfony/deprecation-contracts": "^3.0"
     },
     "require-dev": {
-        "behat/mink-goutte-driver": "^1.1 || ^2.0",
-        "phpspec/phpspec": "^6.0 || ^7.0 || 7.1.x-dev",
-        "mink/webdriver-classic-driver": "^1.0@dev"
+        "behat/mink-browserkit-driver": "^2.0",
+        "phpspec/phpspec": "^8.0",
+        "symfony/browser-kit": "^7.4",
+        "symfony/http-client": "^7.4"
     },
     "replace": {
         "behat/mink-extension": "self.version"
@@ -44,5 +45,11 @@
         "branch-alias": {
             "dev-master": "2.x-dev"
         }
+    },
+    "scripts": {
+        "test": [
+            "vendor/bin/phpspec run -f pretty",
+            "vendor/bin/behat -fprogress --strict"
+        ]
     }
 }