Update env_logger requirement from 0.8 to 0.9

Updates the requirements on [env_logger](https://github.com/env-logger-rs/env_logger) to permit the latest version.
- [Release notes](https://github.com/env-logger-rs/env_logger/releases)
- [Changelog](https://github.com/env-logger-rs/env_logger/blob/main/CHANGELOG.md)
- [Commits](https://github.com/env-logger-rs/env_logger/compare/v0.8.0...v0.9.0)

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

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tokio-postgres/Cargo.toml

@@ -57,7 +57,7 @@ tokio-util = { version = "0.6", features = ["codec"] }
 
 [dev-dependencies]
 tokio = { version = "1.0", features = ["full"] }
-env_logger = "0.8"
+env_logger = "0.9"
 criterion = "0.3"
 
 bit-vec-06 = { version = "0.6", package = "bit-vec" }