Enforce URL constraints for non-URL dependencies (#1565)

## Summary

This was just a missing line -- we have `dependencies.remove(&package);`
in the ~identical branch above, but it must've been an oversight to omit
it here.

Closes https://github.com/astral-sh/uv/issues/1467.

## Test Plan

`cargo test`

crates/uv-resolver/src/pubgrub/dependencies.rs

@@ -121,6 +121,7 @@ impl PubGrubDependencies {
 
                     // Merge the package.
                     if let Some(package) = merge_package(entry.0, &package)? {
+                        dependencies.remove(&package);
                         dependencies.insert(package, version);
                     } else {
                         dependencies.insert(package, version);