Bump tracing-subscriber from 0.2.9 to 0.2.15

Bumps [tracing-subscriber](https://github.com/tokio-rs/tracing) from 0.2.9 to 0.2.15.
- [Release notes](https://github.com/tokio-rs/tracing/releases)
- [Commits](tokio-rs/tracing@tracing-subscriber-0.2.9...tracing-subscriber-0.2.15)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -10,7 +10,7 @@ thiserror = "1.0.20"
 clap = "3.0.0-beta.2"
 dotenv = "0.15.0"
 tracing = "0.1.15"
-tracing-subscriber = "0.2.9"
+tracing-subscriber = "0.2.15"
 serde = "1.0.114"
 serde_json = "1.0.56"
 bincode = "1.3.1"