No need for serde_derive in Rust 2018

Cargo.lock

@@ -1131,6 +1131,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "serde"
 version = "1.0.82"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "serde_derive 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
 [[package]]
 name = "serde_derive"
@@ -1504,7 +1507,6 @@ dependencies = [
  "nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "self_update 0.5.0 (git+https://github.com/r-darwish/self_update?branch=github-extended)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
  "shellexpand 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "structopt 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -12,8 +12,7 @@ edition = "2018"
 directories = "1.0.2"
 failure = "0.1.3"
 failure_derive = "0.1.3"
-serde = "1.0.82"
-serde_derive = "1.0.82"
+serde = { version = "1.0.82", features = ["derive"] }
 toml = "0.4.10"
 which_crate = { version = "2.0.1", package =  "which" }
 shellexpand = "1.0.0"

src/config.rs

@@ -1,7 +1,7 @@
 use super::error::{Error, ErrorKind};
 use directories::BaseDirs;
 use failure::ResultExt;
-use serde_derive::Deserialize;
+use serde::Deserialize;
 use shellexpand;
 use std::collections::BTreeMap;
 use std::fs;