Bump edition to 2024, verified with cargo fix --edition

Author: dimo414

Cargo.toml

@@ -7,7 +7,7 @@ repository = "http://github.com/dimo414/task-mon"
 license = "MIT"
 keywords = ["cron", "healthcheck", "healthchecks", "heartbeat", "monitoring"]
 categories = ["command-line-utilities", "development-tools::debugging"]
-edition = "2018"
+edition = "2024"
 include = [
     "**/*.rs",
     "Cargo.*",