#729 - fix shrink to fit + add test

shrinkToFit was not handled in StyleMerger so it was overwritten by the default cell style
StyleManager didn't add the property to the xml if shrinkToFit was used without alignment or text wrap.
Unit test

src/Spout/Writer/XLSX/Manager/Style/StyleManager.php

@@ -249,7 +249,7 @@ EOD;
 
             $content .= \sprintf(' applyBorder="%d"', $style->shouldApplyBorder() ? 1 : 0);
 
-            if ($style->shouldApplyCellAlignment() || $style->shouldWrapText()) {
+            if ($style->shouldApplyCellAlignment() || $style->shouldWrapText() || $style->shouldShrinkToFit()) {
                 $content .= ' applyAlignment="1">';
                 $content .= '<alignment';
                 if ($style->shouldApplyCellAlignment()) {