Deserializing relative URLs with serde?

It would be nice to be able to deserialize relative URLs with serde, so you could have something like:

#[derive(Deserialize)]
struct Asset {
    url: Url
    ...
}

And then in a directory with /foo/bar.jpg and /foo/baz.toml:

[[assets]]
url = "./bar.jpg"

Serde could be configured to parse the asset url as file:///foo/bar.jpg.

I'm not sure if this is currently possible. Have if missed something? If not, I think it would be possible to sneak in a ParseOptions to the Deserialize impl using a static. I'm willing to write a patch for this. Would it be accepted upstream?

Review the serde Deserialize implementation for Url and the proposed ParseOptions/static configuration against the relative-path TOML example. Determine whether a base directory can be supplied and define completion as deserializing ./bar.jpg to file:///foo/bar.jpg; no test or file path is named in the issue.