[partition] Changing swap choice also changes preview

- When selecting *erase*, you may be able to change the swap
   settings. If so, changing swap settings should change the
   preview.

src/modules/partition/gui/ChoicePage.cpp

@@ -306,6 +306,8 @@ ChoicePage::setupChoices()
 
     connect( this, &ChoicePage::actionChosen,
              this, &ChoicePage::onActionChanged );
+    connect( m_eraseSwapChoices, QOverload<int>::of(&QComboBox::currentIndexChanged),
+             this, &ChoicePage::onActionChanged );
 
     CALAMARES_RETRANSLATE(
         updateSwapChoicesTr( m_eraseSwapChoices );