omni: remove hard Material3 dep in OmniPreferenceTheme

not really needed

Change-Id: I1e95f22d50bc72c7c2fa5aad502d04c44ea43c5d
diff --git a/themes/PreferenceTheme/res/values-v31/styles_preference.xml b/themes/PreferenceTheme/res/values-v31/styles_preference.xml
index a460fb4..5e38ae2 100644
--- a/themes/PreferenceTheme/res/values-v31/styles_preference.xml
+++ b/themes/PreferenceTheme/res/values-v31/styles_preference.xml
@@ -62,7 +62,7 @@
     </style>
 
     <style name="Omni.PreferenceTitle"
-        parent="@style/TextAppearance.Material3.BodyMedium">
+        parent="@android:style/TextAppearance.Material.Medium">
         <item name="android:textSize">@dimen/omni_pref_title_text_size</item>
     </style>