cargo: remove unused lazy_static dependency

This dependency on lazy_static was introduced in d2be307 to avoid
having to bump the minimum supported Rust version. Now that we use
Rust 2018, we no longer have this problem.

Author: mgeisler

Cargo.toml

@@ -29,4 +29,3 @@ toml = "0.5"
 url = "1.5.1"
 itertools = "0.8"
 regex = "1.1"
-lazy_static = "1.2"