Fix various compatibility issues with PHP 8

libs/Captcha/PhraseBuilderInterface.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Gregwar\Captcha;
+
+/**
+ * Interface for the PhraseBuilder
+ *
+ * @author Gregwar <g.passault@gmail.com>
+ */
+interface PhraseBuilderInterface
+{
+    /**
+     * Generates  random phrase of given length with given charset
+     */
+    public function build();
+
+    /**
+     * "Niceize" a code
+     */
+    public function niceize($str);
+}