Fix % issue in about dialog

Closes #1169

Signed-off-by: falkTX <falktx@falktx.com>

resources/ui/carla_about.ui

@@ -716,7 +716,7 @@
           <string>TextLabel</string>
          </property>
          <property name="textFormat">
-          <enum>Qt::PlainText</enum>
+          <enum>Qt::RichText</enum>
          </property>
          <property name="alignment">
           <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignTop</set>