fix(deps): update rust crate cron to 0.15 (#878)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Cargo.lock

@@ -9,5 +9,5 @@ anyhow = "1"
 mizer-node = { path = "../../../node" }
 mizer-clock = { path = "../../../../clock" }
 serde = { version = "1", features = ["derive"] }
-cron = "0.14"
+cron = "0.15"
 chrono = "0.4"