minor #58191 Mitigate PHPUnit deprecations (6.4) (alexandre-daubois)

This PR was merged into the 6.4 branch.

Discussion
----------

Mitigate PHPUnit deprecations (6.4)

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

Like #58190, but for sources added since 6.0.

Commits
-------

cfe67b62bd Mitigate PHPUnit deprecations

Tests/ArgumentResolver/EntityValueResolverTest.php

@@ -173,7 +173,7 @@ public function testResolveWithConversionFailedException()
         $repository->expects($this->once())
             ->method('find')
             ->with('test')
-            ->will($this->throwException(new ConversionException()));
+            ->willThrowException(new ConversionException());
 
         $manager->expects($this->once())
             ->method('getRepository')
@@ -381,7 +381,7 @@ public function testExpressionSyntaxErrorThrowsException()
 
         $language->expects($this->once())
             ->method('evaluate')
-            ->will($this->throwException(new SyntaxError('syntax error message', 10)));
+            ->willThrowException(new SyntaxError('syntax error message', 10));
 
         $this->expectException(\LogicException::class);
         $this->expectExceptionMessage('syntax error message around position 10');