minor #37831 stop using deprecated PHPUnit APIs (xabbuh)

This PR was merged into the 4.4 branch.

Discussion
----------

stop using deprecated PHPUnit APIs

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

Commits
-------

3d209c46e4 stop using deprecated PHPUnit APIs

Author: fabpot

Tests/ErrorHandlerTest.php

@@ -93,10 +93,10 @@ public function testNotice()
             // if an exception is thrown, the test passed
             if (\PHP_VERSION_ID < 80000) {
                 $this->assertEquals(E_NOTICE, $exception->getSeverity());
-                $this->assertRegExp('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
+                $this->assertMatchesRegularExpression('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
             } else {
                 $this->assertEquals(E_WARNING, $exception->getSeverity());
-                $this->assertRegExp('/^Warning: Undefined variable \$(foo|bar)/', $exception->getMessage());
+                $this->assertMatchesRegularExpression('/^Warning: Undefined variable \$(foo|bar)/', $exception->getMessage());
             }
             $this->assertEquals(__FILE__, $exception->getFile());