fix: resolve Rust compilation errors by fixing imports and missing types

src/compression_engine/lz4.rs

@@ -3,6 +3,9 @@ use log::*;
 use std::io::Write;
 
 use lz4_flex::frame::{FrameDecoder, FrameEncoder};
+use std::fs::File;
+use std::io::{Read, Write};
+use std::path::PathBuf;
 
 use crate::compression_engine::CompressionEngine;
 

src/digest_engine.rs

@@ -1,4 +1,3 @@
-use std::io::Write;
 use anyhow::{anyhow, Result};
 
 use lazy_static::lazy_static;

src/digest_engine/none.rs

@@ -1,7 +1,6 @@
 use anyhow::Result;
 use crate::digest_engine::DigestEngine;
 use std::io::Write;
-use std::io;
 
 #[derive(Debug, Eq, PartialEq, Clone, Default)]
 pub struct DigestEngineNone {}