refactor: Update source code based on PHP conventions.

src/Bundle/ChillBudgetBundle/Calculator/CalculatorInterface.php

@@ -1,22 +1,26 @@
 <?php
-/*
- * 
+
+/**
+ * Chill is a software for social workers.
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ *
+ * @see https://www.champs-libres.coop/
  */
+
+declare(strict_types=1);
+
 namespace Chill\AMLI\BudgetBundle\Calculator;
 
 use Chill\AMLI\BudgetBundle\Entity\AbstractElement;
 
-/**
- *
- * @author Julien Fastré <julien.fastre@champs-libres.coop>
- */
 interface CalculatorInterface
 {
     /**
-     * 
      * @param AbstractElement[] $elements
      */
-    public function calculate(array $elements) : ?CalculatorResult;
-    
+    public function calculate(array $elements): ?CalculatorResult;
+
     public function getAlias();
 }