build(deps): Update env_logger requirement from 0.8.1 to 0.9.0 (#2141)

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/v0.8.3...v0.9.0)

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

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

protocols/gossipsub/Cargo.toml

@@ -30,7 +30,7 @@ regex = "1.4.0"
 
 [dev-dependencies]
 async-std = "1.6.3"
-env_logger = "0.8.1"
+env_logger = "0.9.0"
 libp2p-plaintext = { path = "../../transports/plaintext" }
 libp2p-yamux = { path = "../../muxers/yamux" }
 libp2p-mplex = { path = "../../muxers/mplex" }

protocols/identify/Cargo.toml

@@ -20,7 +20,7 @@ wasm-timer = "0.2"
 
 [dev-dependencies]
 async-std = "1.6.2"
-env_logger = "0.8"
+env_logger = "0.9"
 libp2p-mplex = { path = "../../muxers/mplex" }
 libp2p-noise = { path = "../../transports/noise" }
 libp2p-tcp = { path = "../../transports/tcp" }

protocols/relay/Cargo.toml

@@ -29,7 +29,7 @@ wasm-timer = "0.2"
 prost-build = "0.8"
 
 [dev-dependencies]
-env_logger = "0.8.3"
+env_logger = "0.9.0"
 structopt = "0.3.21"
 libp2p = { path = "../.." }
 libp2p-kad = { path = "../kad" }