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::*;
 

crates/searcher/src/lines.rs

@@ -198,8 +198,6 @@ fn preceding_by_pos(
 
 #[cfg(test)]
 mod tests {
-    use grep_matcher::Match;
-
     use super::*;
 
     const SHERLOCK: &'static str = "\

crates/searcher/src/searcher/mod.rs

@@ -7,7 +7,6 @@ use std::{
 };
 
 use {
-    encoding_rs,
     encoding_rs_io::DecodeReaderBytesBuilder,
     grep_matcher::{LineTerminator, Match, Matcher},
 };

crates/searcher/src/testutil.rs

@@ -725,8 +725,6 @@ impl TesterConfig {
 
 #[cfg(test)]
 mod tests {
-    use grep_matcher::{Match, Matcher};
-
     use super::*;
 
     fn m(start: usize, end: usize) -> Match {