Clippy-fix explicit auto-deref

Seems like these can be safely fixed. With one, I was particularly
surprised -- `Some(pats) => &**pats,` in body.rs?

```
cargo clippy --fix -- -A clippy::all -D clippy::explicit_auto_deref
```

crates/project-model/src/manifest_path.rs

@@ -40,7 +40,7 @@ impl ops::Deref for ManifestPath {
     type Target = AbsPath;
 
     fn deref(&self) -> &Self::Target {
-        &*self.file
+        &self.file
     }
 }