smaller font size in notebook selector

Signed-off-by: Le Tan <[email protected]>

src/resources/vnote.qss

@@ -69,7 +69,7 @@ QDockWidget::close-button:hover, QDockWidget::float-button:hover {
 QComboBox#NotebookSelector {
     border: none;
     background-color: @base-background;
-    font-size: 20px;
+    font-size: 15px;
     padding-top: 3px;
     padding-bottom: 3px;
     icon-size: 30px;