Reduce the file name length to avoid exception

Author: introfog

src/test/java/com/itextpdf/html2pdf/css/w3c/css_grid/GridTracksStretchedWithDifferentFlexFactorsSumTest.java

@@ -32,6 +32,6 @@ This file is part of the iText (R) project.
 public class GridTracksStretchedWithDifferentFlexFactorsSumTest extends W3CCssGridTest {
     @Override
     protected String getHtmlFileName() {
-        return "grid-tracks-stretched-with-different-flex-factors-sum.html";
+        return "tracks-stretched-diff-flex-factors-sum.html";
     }
 }