Replaced deprecated "assertRegExp" test method by assertMatchesRegularExpression.

Author: hazington

tests/PhpWordTests/Writer/Word2007/Part/DocumentTest.php

@@ -408,7 +408,7 @@ public function testWriteImage(): void
         // behind
         $element = $doc->getElement('/w:document/w:body/w:p[2]/w:r/w:pict/v:shape');
         $style = $element->getAttribute('style');
-        self::assertRegExp('/z\-index:\-[0-9]*/', $style);
+        self::assertMatchesRegularExpression('/z\-index:\-[0-9]*/', $style);
 
         // square
         $element = $doc->getElement('/w:document/w:body/w:p[4]/w:r/w:pict/v:shape/w10:wrap');