Fix various compatibility issues with PHP 8

libs/Captcha/CaptchaBuilderInterface.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Gregwar\Captcha;
+
+/**
+ * A Captcha builder
+ */
+interface CaptchaBuilderInterface
+{
+    /**
+     * Builds the code
+     */
+    public function build($width, $height, $font, $fingerprint);
+
+    /**
+     * Saves the code to a file
+     */
+    public function save($filename, $quality);
+
+    /**
+     * Gets the image contents
+     */
+    public function get($quality);
+
+    /**
+     * Outputs the image
+     */
+    public function output($quality);
+}