Update clippy

Author: Manishearth

Cargo.lock

@@ -378,7 +378,6 @@ dependencies = [
  "rustc_tools_util 0.1.1",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -399,7 +398,6 @@ dependencies = [
  "regex-syntax 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-normalization 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",