fix: ensure local Headers implementation is loaded in favor of lamina…

…s-mail implementation

- Use `files` autoloader to load the local `Headers` version
- Ensure that the import for `ReturnTypeWillChange` attribute is not removed by phpcs

Signed-off-by: Matthew Weier O'Phinney <matthew@weierophinney.net>

composer.json

@@ -36,9 +36,11 @@
         }
     },
     "autoload-dev": {
+        "files": [
+            "test/TestAsset/Mail/Headers.php"
+        ],
         "psr-4": {
-            "LaminasTest\\Mime\\": "test/",
-            "Laminas\\Mail\\": "test/TestAsset/Mail/"
+            "LaminasTest\\Mime\\": "test/"
         }
     },
     "scripts": {

test/TestAsset/Mail/Headers.php

@@ -1,4 +1,4 @@
-<?php // phpcs:disable WebimpressCodingStandard.NamingConventions.ValidVariableName.NotCamelCaps
+<?php // phpcs:disable WebimpressCodingStandard.NamingConventions.ValidVariableName.NotCamelCaps,SlevomatCodingStandard.Namespaces.UnusedUses.UnusedUse
 
 declare(strict_types=1);
 
@@ -10,6 +10,7 @@
 use Laminas\Loader\PluginClassLocator;
 use Laminas\Mail\Header\GenericHeader;
 use Laminas\Mail\Header\HeaderInterface;
+use ReturnTypeWillChange;
 use Traversable;
 
 use function array_keys;