Update the nix dependency

.travis.yml

@@ -2,8 +2,6 @@ language: rust
 dist: xenial
 
 rust:
-    - "1.34.2"
-    - "1.35.0"
     - "1.36.0"
     - "1.37.0"
     - "1.38.0"

README.md

@@ -58,7 +58,7 @@ This project provides the following man pages:
 
 ## Build from source
 
-In order to compile ACMEd, you will need the [Rust](https://www.rust-lang.org/) compiler and its package manager, Cargo. The minimal required Rust version is 1.34.2, although it is recommended to use the latest stable one.
+In order to compile ACMEd, you will need the [Rust](https://www.rust-lang.org/) compiler and its package manager, Cargo. The minimal required Rust version is 1.36.0, although it is recommended to use the latest stable one.
 
 ACMEd depends OpenSSL 1.1.0 or higher.
 

acmed/Cargo.toml

@@ -30,4 +30,4 @@ serde = { version = "1.0", features = ["derive"] }
 toml = "0.5"
 
 [target.'cfg(unix)'.dependencies]
-nix = "0.15"
+nix = "0.17"