Fix tum read (#584)

* Fix tum read

* test(oma-tum): use lists dir, not sysroot

Author: eatradish

oma-tum/examples/tum/var/lib/apt/lists/updates.json renamed to oma-tum/examples/tum/updates.json

@@ -392,7 +392,7 @@ impl CommitChanges<'_> {
 
         if check_tum {
             #[cfg(feature = "aosc")]
-            let tum = oma_tum::get_tum(Path::new(&sysroot))?;
+            let tum = oma_tum::get_tum(get_lists_dir(&AptConfig::new()))?;
 
             #[cfg(feature = "aosc")]
             let matches_tum = Some(oma_tum::get_matches_tum(&tum, &op));