fix clippy lint deprecation

Author: Firestar99

.cargo/config.toml

@@ -40,7 +40,7 @@ rustflags = [
     "-Wclippy::map_err_ignore",
     "-Wclippy::map_flatten",
     "-Wclippy::map_unwrap_or",
-    "-Wclippy::match_on_vec_items",
+    "-Wclippy::indexing_slicing",
     "-Wclippy::match_same_arms",
     "-Wclippy::match_wild_err_arm",
     "-Wclippy::match_wildcard_for_single_variants",