feat: use sets etc.

rust/src/model/local.rs

@@ -1,3 +1,4 @@
+use std::collections::BTreeSet;
 use serde::Deserialize;
 use crate::pkg::PkgKeyVersion;
 
@@ -9,5 +10,5 @@ pub struct PackageManifest {
     pub name: String,
     pub version_number: String,
     pub description: String,
-    pub dependencies: Vec<PkgKeyVersion>
+    pub dependencies: BTreeSet<PkgKeyVersion>
 }