layout: Drop theme attribute from toolbar

Conflicts with DynamicTheme in dark mode

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

app/src/main/res/layout/fragment_installer.xml

@@ -31,7 +31,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:minHeight="?attr/actionBarSize"
-        android:theme="?attr/actionBarTheme"
         app:navigationIcon="@drawable/ic_arrow_back"
         app:title="@string/pref_install_mode_title" />
 
@@ -46,4 +45,4 @@
         app:itemSpacing="@dimen/margin_small"
         tools:listitem="@layout/view_installer" />
 
-</LinearLayout>
+</LinearLayout>