build(deps): bump failure from 0.1.7 to 0.1.8

Bumps [failure](https://github.com/rust-lang-nursery/failure) from 0.1.7 to 0.1.8.
- [Release notes](https://github.com/rust-lang-nursery/failure/releases)
- [Changelog](https://github.com/rust-lang-nursery/failure/blob/master/RELEASES.md)
- [Commits](https://github.com/rust-lang-nursery/failure/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Cargo.lock

@@ -292,9 +292,9 @@ dependencies = [
 
 [[package]]
 name = "failure"
-version = "0.1.7"
+version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8529c2421efa3066a5cbd8063d2244603824daccb6936b079010bb2aa89464b"
+checksum = "d32e9bd16cc02eae7db7ef620b392808b89f6a5e16bb3497d159c6b92a0f4f86"
 dependencies = [
  "backtrace",
  "failure_derive",