Use correct pyproject.toml path in warnings (#5069)

One part of #5068. I think the other is not warning when the version is
dynamic, but this fix is needed either way.

crates/uv-distribution/src/workspace.rs

@@ -777,7 +777,7 @@ async fn find_workspace(
             // We require that a `project.toml` file either declares a workspace or a project.
             warn_user!(
                 "pyproject.toml does not contain `project` table: `{}`",
-                workspace_root.simplified_display()
+                pyproject_path.simplified_display()
             );
             Ok(None)
         };