Tell the user when --recursive is traversing folders

After calling `cargo-sweep` with `--recursive` in a big folder, the tool
usually stays silent for a long time leaving the user wondering what's
going on

To solve that, I added a log that tells that `cargo-sweep` is traversing
recursively directories, that's why it's taking long

src/main.rs

@@ -149,6 +149,7 @@ fn main() -> anyhow::Result<()> {
     };
 
     let processed_paths = if args.recursive {
+        info!("Searching recursively for Rust project folders");
         paths
             .iter()
             .flat_map(|path| find_cargo_projects(path, args.hidden))