Auto merge of #14487 - ehuss:fix-elided-lifetime, r=epage

Fix elided lifetime

This fixes an issue with the recent nightly that has added a lint (rust-lang/rust#129207) that warns about the lack of a lifetime, which looks like:

```
warning: elided lifetime has a name
   --> src/cargo/core/workspace.rs:580:66
    |
580 |     pub fn default_members<'a>(&'a self) -> impl Iterator<Item = &Package> {
    |                            -- lifetime `'a` declared here        ^ this elided lifetime gets resolved as `'a`
    |
    = note: `#[warn(elided_named_lifetimes)]` on by default
```

src/cargo/core/workspace.rs

@@ -577,7 +577,7 @@ impl<'gctx> Workspace<'gctx> {
     }
 
     /// Returns an iterator over default packages in this workspace
-    pub fn default_members<'a>(&'a self) -> impl Iterator<Item = &Package> {
+    pub fn default_members<'a>(&'a self) -> impl Iterator<Item = &'a Package> {
         let packages = &self.packages;
         self.default_members
             .iter()