fix: package lock fingerprint

tests/Features/Fixture.php

@@ -1,12 +1,14 @@
 <?php
 
-it('may return a file path', function () {
+declare(strict_types=1);
+
+it('may return a file path', function (): void {
     $file = fixture('phpunit-in-isolation.xml');
 
     expect($file)->toBeString()
         ->toBeFile();
 });
 
-it('may throw an exception if the file does not exist', function () {
+it('may throw an exception if the file does not exist', function (): void {
     fixture('file-that-does-not-exist.php');
 })->throws(InvalidArgumentException::class);