Use tracing instead of slog for better ergonomics

src/count.rs

@@ -1,10 +1,12 @@
 use crate::error::Result;
 use std::{fs::read_dir, path::Path, result::Result as StdResult};
 
+#[instrument]
 pub(crate) fn count_repositories<P>(repo_path: P) -> Result<usize>
 where
-    P: AsRef<Path>,
+    P: AsRef<Path> + std::fmt::Debug,
 {
+    trace!("Counting repositories");
     std::fs::create_dir_all(&repo_path)?;
     Ok(read_dir(repo_path)?
         .filter_map(StdResult::ok)