Avoid updating incorrect dependencies for sorted uv add (#6939)

## Summary

The indexes stored in the edits is wrong now that we add dependencies
out-of-order.

Closes https://github.com/astral-sh/uv/issues/6933.

crates/uv-workspace/src/pyproject.rs

@@ -486,7 +486,7 @@ impl Source {
 }
 
 /// The type of a dependency in a `pyproject.toml`.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum DependencyType {
     /// A dependency in `project.dependencies`.
     Production,