[5.x] Fix deprecation warning from regex operator (#11337)

* Fix deprecation warning from regex operator

* cast for consistency with similar method a few lines above

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Co-authored-by: Jason Varga <[email protected]>

Author: duncanmcclean

src/Query/Builder.php

@@ -699,7 +699,7 @@ protected function filterTestNotLike($item, $like)
 
     protected function filterTestLikeRegex($item, $pattern)
     {
-        return preg_match("/{$pattern}/im", $item);
+        return preg_match("/{$pattern}/im", (string) $item);
     }
 
     protected function filterTestNotLikeRegex($item, $pattern)