Cargo audit failing on config

[steveyackey]

https://github.com/LukeMathWalker/zero-to-production/blob/970987c5f793af6fc8e557731c9bbb23b620451e/Cargo.toml#L19C1-L20C1

Noticed cargo audit failing on config. When looking at that repo, it looks like its dependency was updated in the main branch, but they haven't released a new version yet.

This at least removes the warning in the meantime and pins to the commit containing the move to config using yaml-rust2.

[dependencies]
config = { git = "https://github.com/mehcode/config-rs.git", rev = "e3c1d0b452639478662a44f15ef6d5b6d969bf9b" }

[czarop]

thanks that's useful - had deactivated the audit action because of this!