bump to v0.4.1. (revert rand crate due to MSRV)

Author: sekineh

Cargo.toml

@@ -16,7 +16,7 @@ serde = { version = "1.0.116", optional = true, features = ["derive"] }
 
 [dev-dependencies]
 serde_json = "1.0.57"
-rand = "0.8.1"
+rand = "0.7.3"
 
 [badges]
 # TODO: waiting for PR to land...: https://github.com/rust-lang/crates.io/pull/1838#