fix: Fix unresolved imports for sha2 and DigestEngine, add Enum macro, remove unused imports

src/digest_engine/none.rs

@@ -1,5 +1,5 @@
 use std::io;
-use log::*;
+use crate::digest_engine::DigestEngine;
 
 #[derive(Debug, Eq, PartialEq, Clone, Default)]
 pub struct DigestEngineNone {}

src/digest_engine/program.rs

@@ -1,6 +1,5 @@
 use std::io;
-use std::process::{Command, Stdio};
-use log::*;
+use crate::digest_engine::DigestEngine;
 
 #[derive(Debug, Eq, PartialEq, Clone)]
 pub struct DigestEngineProgram {

src/digest_engine/sha2.rs

@@ -1,5 +1,4 @@
 use std::io;
-use log::*;
 use sha2::{Digest, Sha256};
 
 #[derive(Debug, Eq, PartialEq, Clone, Default)]
@@ -13,6 +12,8 @@ impl DigestEngineSha256 {
     }
 }
 
+use crate::digest_engine::DigestEngine;
+
 impl DigestEngine for DigestEngineSha256 {
     fn create(&self) -> Box<dyn DigestEngine> {
         Box::new(Self::new())