[ui] rename the min/max widget group box title

Since there is no more loading involved through
the min/max widget, rename it to:
"Min /max values settings"

Author: nirvn

src/ui/qgsrasterminmaxwidgetbase.ui

@@ -29,7 +29,7 @@
    <item>
     <widget class="QgsCollapsibleGroupBox" name="mLoadMinMaxValuesGroupBox">
      <property name="title">
-      <string>Load min/max values</string>
+      <string>Min / max values settings</string>
      </property>
      <property name="flat">
       <bool>true</bool>