Increased the height of the welcome wizard screen.

Discussed with UX what the best approach would be.
Both came to the conclusion that this is the simplest
and more aesthetic approach.

The extra white space at the bottom and height of the
first screen is still acceptable according to UX.

Contributes to CURA-8290_whats_new_text

resources/qml/WelcomePages/WhatsNewContent.qml

@@ -135,7 +135,7 @@ Item
         anchors
         {
             bottom: whatsNewNextButton.top
-            bottomMargin: UM.Theme.getSize("narrow_margin").height
+            bottomMargin: UM.Theme.getSize("wide_margin").height
             horizontalCenter: parent.horizontalCenter
         }
 

resources/themes/cura-light/theme.json

@@ -581,7 +581,7 @@
 
         "monitor_preheat_temperature_control": [4.5, 2.0],
 
-        "welcome_wizard_window": [46, 45],
+        "welcome_wizard_window": [46, 50],
         "modal_window_minimum": [60.0, 45],
         "license_window_minimum": [45, 45],
         "wizard_progress": [10.0, 0.0],