cargo upgrade --manifest-path only works with absolute paths

[epage]

We try to find the path in the CargoMetadata but it won't match.

cargo-set-version should have the needed logic for this. I guess an alternative to dunce::canonicalize is same_file.

When fixing this, we should copy tests/cmd/upgrade/workspace_member_cwd.* into a _manifest_path test that specifies the manifest path instead of relying on cwd.