Update PreferenceCategory headers to use headline font.

Medium weight.

Bug: 70296667
Test: visual
Change-Id: I879f5524920050e0a12b094d8ad0e9bcf72fd24c
diff --git a/packages/SettingsLib/res/layout/preference_category_material_settings.xml b/packages/SettingsLib/res/layout/preference_category_material_settings.xml
index 245e3b7..1086106 100644
--- a/packages/SettingsLib/res/layout/preference_category_material_settings.xml
+++ b/packages/SettingsLib/res/layout/preference_category_material_settings.xml
@@ -50,6 +50,7 @@
             android:layout_marginTop="16dp"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
+            android:fontFamily="@*android:string/config_headlineFontFamilyMedium"
             android:textAppearance="@android:style/TextAppearance.Material.Body2"
             android:textAlignment="viewStart"
             android:textColor="?android:attr/colorAccent"