chore: fix up the README example (#194)

Due to the this commit:

commit bc96471
Author: DaniPopes <[email protected]>
Date:   Sat Jun 29 00:20:26 2024 +0200

    chore: remove most impl AsRef<str,Path> (#157)

The interface for `hardhat()` is updated to `&Path`.

---------

Co-authored-by: DaniPopes <[email protected]>

README.md

@@ -53,10 +53,11 @@ Example usage:
 
 ```rust,ignore
 use foundry_compilers::{Project, ProjectPathsConfig};
+use std::path::Path;
 
 // configure the project with all its paths, solc, cache etc.
 let project = Project::builder()
-    .paths(ProjectPathsConfig::hardhat(env!("CARGO_MANIFEST_DIR")).unwrap())
+    .paths(ProjectPathsConfig::hardhat(Path::new(env!("CARGO_MANIFEST_DIR"))).unwrap())
     .build(Default::default())
     .unwrap();
 let output = project.compile().unwrap();