message: fix: Make v1 field private
diff: @@ -29,7 +29,7 @@ pub struct Empty {}
  #[derive(Deserialize, Serialize)]
  pub struct CrateListingV1 {
  - pub v1: BTreeMap<PackageId, BTreeSet<String>>,
  + v1: BTreeMap<PackageId, BTreeSet<String>>,
  }
  pub fn resolve_root(flag: Option<&str>, config: &Config) -> CargoResult<Filesystem> {
  