Specify rust-version in Cargo.toml

- We need to use a version that is compatible with the rust version available in rhel9
- rhel9 currently ships rust 1.75
- Regenerated lockfile to make sure it is also compatible with the specified rust-version
- For more information, refer to:
    - https://doc.rust-lang.org/cargo/reference/rust-version.html
    - rust-lang/cargo#12861
    - rust-lang/cargo#13503

Author: fontivan

Cargo.lock

@@ -1,5 +1,7 @@
 [package]
 name = "recert"
+# we need to compile with a rust version that is compatible with rhel9
+rust-version = "1.75"
 version = "0.1.0"
 edition = "2021"