refactor: Update IndexPackage to use Cow for links

Signed-off-by: 0xPoe <techregister@pm.me>

Author: 0xPoe

src/cargo/sources/registry/index/mod.rs

@@ -226,7 +226,7 @@ pub struct IndexPackage<'a> {
     ///
     /// Added early 2018 (see <https://github.com/rust-lang/cargo/pull/4978>),
     /// can be `None` if published before then.
-    pub links: Option<InternedString>,
+    pub links: Option<Cow<'a, str>>,
     /// Required version of rust
     ///
     /// Corresponds to `package.rust-version`.
@@ -291,13 +291,8 @@ impl IndexPackage<'_> {
                 )
             })
             .collect::<BTreeMap<_, _>>();
-        let mut summary = Summary::new(
-            pkgid,
-            deps,
-            &features,
-            self.links,
-            self.rust_version.clone(),
-        )?;
+        let links = self.links.as_ref().map(|l| InternedString::new(&l));
+        let mut summary = Summary::new(pkgid, deps, &features, links, self.rust_version.clone())?;
         summary.set_checksum(self.cksum.clone());
         Ok(summary)
     }