Update redis requirement from 0.27 to 0.28

Updates the requirements on [redis](https://github.com/redis-rs/redis-rs) to permit the latest version.
- [Release notes](https://github.com/redis-rs/redis-rs/releases)
- [Commits](redis-rs/redis-rs@redis-0.27.0...redis-0.28.0)

---
updated-dependencies:
- dependency-name: redis
  dependency-type: direct:production
...

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

Author: dependabot[bot]

redis/Cargo.toml

@@ -9,7 +9,7 @@ repository = "https://github.com/djc/bb8"
 
 [dependencies]
 bb8 = { version = "0.9", path = "../bb8" }
-redis = { version = "0.27", default-features = false, features = ["tokio-comp"] }
+redis = { version = "0.28", default-features = false, features = ["tokio-comp"] }
 
 [dev-dependencies]
 futures-util = "0.3.15"