Fix implicit nullable parameters deprecation in unit tests

Author: PhrozenByte

tests/TestCase.php

@@ -52,7 +52,7 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
     protected function mockConstraint(
         $constraint,
         array $invocationRules = [],
-        array $evaluateParameters = null
+        ?array $evaluateParameters = null
     ) {
         if (!($constraint instanceof Constraint)) {
             return $constraint;

tests/Unit/ArrayAssertsTraitTest.php

@@ -450,7 +450,7 @@ public function dataProviderArrayHasItemWithFail(): array
     private function mockConstraintInstance(
         string $className,
         array $constructorArguments = [],
-        array $evaluateArguments = null
+        ?array $evaluateArguments = null
     ): MockInterface {
         $instanceMock = Mockery::mock('overload:' . $className, Constraint::class);