Fix implicit nullable variables causing a deprecation warning in PHP 8.4

Author: tobias-93

src/Builder/BuilderInterface.php

@@ -49,7 +49,7 @@ function getDefaultTemplateName(): string;
      *
      * @return string   The short classname.
      */
-    function getSimpleClassName(string $class = null): string;
+    function getSimpleClassName(?string $class = null): string;
 
     function setOutputName(string $outputName): void;
 

src/Builder/Generator.php

@@ -41,7 +41,7 @@ class Generator
      *
      * @param string|null $baseTempDir Existing base directory for temporary template files
      */
-    public function __construct(string $baseTempDir = null)
+    public function __construct(?string $baseTempDir = null)
     {
         if (null === $baseTempDir) {
             $baseTempDir = sys_get_temp_dir();

src/Extension/TwigPrintExtension.php

@@ -186,7 +186,7 @@ public function getEchoExtends(string $name): string
      * {{ echo_for('item', 'myListObject', 'key') }}
      *      => {% for key,item in myListObject %}
      */
-    public function getEchoFor(string $object, string $in, string $key = null): string
+    public function getEchoFor(string $object, string $in, ?string $key = null): string
     {
         return strtr(
             '{% for %%key%%%%object%% in %%in%% %}',