Fix test on Windows

Author: marcphilipp

platform-tests/src/test/java/org/junit/platform/reporting/open/xml/OpenTestReportGeneratingListenerTests.java

@@ -141,7 +141,7 @@ void writesValidXmlReport(@TempDir Path tempDirectory) throws Exception {
 				    </e:reported>
 				    <e:reported id="2" time="${xmlunit.isDateTime}">
 				        <attachments>
-				            <file time="${xmlunit.isDateTime}" path="../test.txt" mediaType="text/plain" />
+				            <file time="${xmlunit.isDateTime}" path="${xmlunit.matchesRegex(\\.\\.[/\\\\]test.txt)}" mediaType="text/plain" />
 				        </attachments>
 				    </e:reported>
 				    <e:reported id="2" time="${xmlunit.isDateTime}">