chore: 2018 edition and remove unused crate chrono

Cargo.toml

@@ -2,6 +2,7 @@
 name = "cargo-sweep"
 description = "A tool for cleaning unused build files created by Cargo"
 version = "0.3.0"
+edition = "2018"
 authors = ["holmgr <viktor.holmgren@gmail.com>"]
 keywords = ["tool", "cli", "cargo"]
 license = "MIT"
@@ -12,7 +13,6 @@ readme = "README.md"
 clap = "2.32.0"
 walkdir = "2"
 failure = "0.1.3"
-chrono = "0.4.6"
 log = "0.4.6"
 fern = { version = "0.5", features = ["colored"] }
 cargo_metadata = "0.6.1"

src/fingerprint.rs

@@ -1,5 +1,7 @@
 #![allow(deprecated)]
 use failure::{bail, Error};
+use log::{debug, info, warn};
+use serde_derive::Deserialize;
 use serde_json::from_str;
 use std::collections::HashSet;
 use std::hash::{Hash, Hasher, SipHasher};

src/main.rs

@@ -1,19 +1,6 @@
-extern crate chrono;
-extern crate clap;
-extern crate failure;
-extern crate walkdir;
-#[macro_use]
-extern crate log;
-extern crate cargo_metadata;
-extern crate fern;
-#[macro_use]
-extern crate serde_derive;
-extern crate serde;
-extern crate serde_json;
-
 use clap::{App, Arg, ArgGroup, SubCommand};
 use fern::colors::{Color, ColoredLevelConfig};
-use fingerprint::{remove_not_built_with, remove_older_then};
+use log::{debug, error, info};
 use std::{
     env,
     path::{Path, PathBuf},
@@ -24,6 +11,7 @@ use walkdir::WalkDir;
 mod fingerprint;
 mod stamp;
 mod util;
+use self::fingerprint::{remove_not_built_with, remove_older_then};
 use self::stamp::Timestamp;
 use self::util::format_bytes;
 
@@ -87,9 +75,7 @@ fn is_hidden(entry: &walkdir::DirEntry) -> bool {
 fn find_cargo_projects(root: &Path, include_hidden: bool) -> Vec<PathBuf> {
     let mut target_paths = std::collections::BTreeSet::new();
 
-    let mut iter = WalkDir::new(root)
-        .min_depth(1)
-        .into_iter();
+    let mut iter = WalkDir::new(root).min_depth(1).into_iter();
 
     while let Some(entry) = iter.next() {
         if let Ok(entry) = entry {

src/stamp.rs

@@ -1,4 +1,5 @@
 use failure::Error;
+use serde_derive::{Deserialize, Serialize};
 use serde_json::{from_str, to_string};
 use std::{
     fs::{remove_file, File},