chore: rust 2021 edition

Signed-off-by: Chojan Shang <[email protected]>

Author: PsiACE

Cargo.toml

@@ -10,7 +10,7 @@ homepage = "https://github.com/ritelabs/failpoints"
 documentation = "https://docs.rs/failpoints"
 description = "Failpoints for rust. Another fail-rs."
 categories = ["development-tools::testing"]
-edition = "2018"
+edition = "2021"
 exclude = ["/.github/*"]
 
 [dependencies]

examples/failpoint/Cargo.toml

@@ -2,7 +2,7 @@
 name = "failpoint"
 version = "0.1.0"
 authors = ["Chojan Shang <[email protected]>"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html