Add filter for lower case first - Close #6

Author: sandrokeil

src/Filter/LowerCaseFirst.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * @see       https://github.com/open-code-modeling/php-filter for the canonical source repository
+ * @copyright https://github.com/open-code-modeling/php-filter/blob/master/COPYRIGHT.md
+ * @license   https://github.com/open-code-modeling/php-filter/blob/master/LICENSE.md MIT License
+ */
+
+declare(strict_types=1);
+
+namespace OpenCodeModeling\Filter\Filter;
+
+final class LowerCaseFirst extends AbstractFilter
+{
+    public function __invoke(string $value): string
+    {
+        return \lcfirst(($this->filter)($value));
+    }
+}