Update Tests

tests/LaravelAgeTest.php

@@ -81,3 +81,19 @@
     $encrypted = $age->encrypt($message);
     $decrypted = $age->decrypt($encrypted);
 })->throws(Exception::class);
+
+it('runs usage code from readme', function () {
+    $message = 'Hello World!';
+
+    $age = LaravelAge::generateKeypair();
+    $privateKey = $age->getPrivateKey();
+    $publicKey = $age->getPublicKey();
+
+    $age2 = new LaravelAge(publicKey: $publicKey);
+    $encrypted_message = $age2->encrypt($message);
+
+    $age3 = new LaravelAge(privateKey: $privateKey);
+    $decrypted_message = $age3->decrypt($encrypted_message);
+
+    expect($message)->toBe($decrypted_message);
+});