Bump config from 0.14.1 to 0.15.4

Bumps [config](https://github.com/rust-cli/config-rs) from 0.14.1 to 0.15.4.
- [Changelog](https://github.com/rust-cli/config-rs/blob/main/CHANGELOG.md)
- [Commits](rust-cli/config-rs@v0.14.1...v0.15.4)

---
updated-dependencies:
- dependency-name: config
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -9,7 +9,7 @@ description = "Discord bot to remind users to use backticks"
 [dependencies]
 anyhow = "1.0.95"
 async-trait = "0.1.48"
-config = "0.14.1"
+config = "0.15.4"
 futures = "0.3.31"
 log = "0.4.22"
 pretty_env_logger = "0.5.0"