chore: clean up types and PHP 8-ify the code

tests/Generator/RandomLibAdapterTest.php

@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace Ramsey\Uuid\Test\Generator;
 
 use Mockery;
+use Mockery\MockInterface;
 use Ramsey\Uuid\Generator\RandomLibAdapter;
 use Ramsey\Uuid\Test\TestCase;
 use RandomLib\Factory as RandomLibFactory;
@@ -34,8 +35,11 @@ class RandomLibAdapterTest extends TestCase
      */
     public function testAdapterWithoutGeneratorGreatesGenerator(): void
     {
+        $generator = Mockery::mock(Generator::class);
+
+        /** @var RandomLibFactory&MockInterface $factory */
         $factory = Mockery::mock('overload:' . RandomLibFactory::class);
-        $factory->shouldReceive('getHighStrengthGenerator')->once();
+        $factory->expects()->getHighStrengthGenerator()->andReturns($generator);
 
         $this->assertInstanceOf(RandomLibAdapter::class, new RandomLibAdapter());
     }