style: fix new lints

The Rust compiler seems to have gotten smarter at finding unused or
redundant imports.

crates/searcher/src/line_buffer.rs

@@ -548,7 +548,7 @@ fn replace_bytes(
 
 #[cfg(test)]
 mod tests {
-    use bstr::{ByteSlice, ByteVec};
+    use bstr::ByteVec;
 
     use super::*;