fix: use Authorizer::to_string for inspection

`to_string` provides a more complete view than `dump_code`, including facts origins.

Before biscuit-auth/biscuit-rust#195, `to_string()` did not include authorizer facts on snapshots  (before running `authorize`). This is not an issue with the latest biscuit-rust version (`4.1.1`), so it is safe to use `to_string()`

src/inspect.rs

@@ -555,7 +555,7 @@ pub fn handle_inspect_snapshot_inner(
 
     let mut authorizer = read_snapshot_from(&snapshot_from)?;
     let snapshot_description = SnapshotDescription {
-        code: authorizer.dump_code(),
+        code: authorizer.to_string(),
         iterations: authorizer.iterations(),
         elapsed_micros: authorizer.execution_time().as_micros(),
     };