Updates to NamelessMatchSpec to allow deserializing

[travishathaway]

While working on this issue:

• Support specifying channel per package (e.g. <channel>::<package>) prefix-dev/pixi#76

I realized that I was going to need to be able to deserialize the NamelessMatchSpec struct from a mapping. I believe the easiest way to allow this is by adding Deserialize to derive in the correct places.

On NamelessMatchSpec I also chose to use DisplayFromStr for version and build because I believe that's the easiest way to do it. I would be happy to change it if that's not right though.

Below is my simplified use case:

use std::fs;
use std::path::PathBuf;

use indexmap::IndexMap;
use clap::{Parser};
use serde::Deserialize;
use serde_with::{serde_as, DisplayFromStr, PickFirst};
use rattler_conda_types::NamelessMatchSpec;

#[derive(Parser)]
#[command(name = "tt - TOML test")]
#[command(author = "Travis Hathaway")]
#[command(version = "0.1.0")]
#[command(about = "Tests with TOML parsing")]
struct Cli {
    /// TOML File
    toml_file: PathBuf,
}

/// Describes the contents of a test project manifest.
#[serde_as]
#[derive(Debug, Clone, Deserialize)]
pub struct MyManifest {
    #[serde_as(as = "IndexMap<_, PickFirst<(_, DisplayFromStr)>>")]
    dependencies: IndexMap<String, NamelessMatchSpec>
}


fn main() -> Result<(), Box<dyn std::error::Error>>{
    let cli = Cli::parse();

    println!("{:?}\n", cli.toml_file);

    if cli.toml_file.exists() {
        let contents = fs::read_to_string(cli.toml_file)?;
        let manifest = toml_edit::de::from_str::<MyManifest>(&contents)?;

        println!("Dependencies:");
        println!("{:?}", manifest.dependencies);

    } else {
        println!("File does not exist");
    }

    Ok(())
}

[baszalmstra]

Thanks @travishathaway!