Added phpunit with tests, and updated dependencies

Author: sebprt

composer.json

@@ -10,10 +10,14 @@
         }
     ],
     "minimum-stability": "dev",
+    "prefer-stable": true,
     "require": {
         "php": "^8.0",
         "symfony/expression-language": "^5.2"
     },
+    "require-dev": {
+        "phpunit/phpunit": "^9.0"
+    },
     "autoload": {
         "psr-4": {
             "Kiboko\\Component\\StringExpressionLanguage\\": "src/"
@@ -28,5 +32,8 @@
         "branch-alias": {
             "dev-master": "0.1.x-dev"
         }
+    },
+    "config": {
+        "bin-dir": "bin"
     }
 }