add phpstan and correct till level 5

Author: kcassam

composer.json

@@ -36,6 +36,7 @@
         "illuminate/support": "^8.0 || ^9.0 || ^10.0 || ^11.0"
     },
     "require-dev": {
+        "larastan/larastan": "^2.0",
         "laravel/legacy-factories": "^1.0.4",
         "laravel/pint": "^1.0",
         "mockery/mockery": "^1.3.3",
@@ -66,6 +67,7 @@
     },
     "scripts": {
         "fix": "@php vendor/bin/pint",
+        "phpstan": "@php vendor/bin/phpstan analyse",
         "test": "@php vendor/bin/phpunit",
         "test-coverage": "@php vendor/bin/phpunit --coverage-html=build"
     }

phpstan.neon

@@ -0,0 +1,18 @@
+includes:
+    - vendor/larastan/larastan/extension.neon
+
+parameters:
+
+    paths:
+        - src/
+
+    # Level 9 is the highest level
+    level: 6
+
+#    ignoreErrors:
+#        - '#PHPDoc tag @var#'
+#
+#    excludePaths:
+#        - ./*/*/FileToBeExcluded.php
+#
+#    checkMissingIterableValueType: false

src/Translatable/Exception/LocalesNotDefinedException.php

@@ -6,6 +6,6 @@ class LocalesNotDefinedException extends \Exception
 {
     public static function make(): self
     {
-        return new static('Please make sure you have run `php artisan vendor:publish --provider="Astrotomic\Translatable\TranslatableServiceProvider"` and that the locales configuration is defined.');
+        return new self('Please make sure you have run `php artisan vendor:publish --provider="Astrotomic\Translatable\TranslatableServiceProvider"` and that the locales configuration is defined.');
     }
 }