Drop Laravel v12 support, keep only Laravel v13

Co-authored-by: chinleung <19669331+chinleung@users.noreply.github.com>

Author: Copilot

composer.json

@@ -21,11 +21,11 @@
     "require": {
         "php": "^8.3",
         "chinleung/laravel-locales": "^2.0",
-        "illuminate/support": "^12.0|^13.0"
+        "illuminate/support": "^13.0"
     },
     "require-dev": {
-        "orchestra/testbench": "^8.0|^9.0|^10.0|^11.0",
-        "phpunit/phpunit": "^9.5.10|^10.5|^11.5.3|^12.5.12"
+        "orchestra/testbench": "^11.0",
+        "phpunit/phpunit": "^12.5.12"
     },
     "autoload": {
         "psr-4": {