Auto merge of #4277 - rust-lang:renovate/tokio-1.x, r=Turbo87

Update Rust crate tokio to 1.15.0

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [tokio](https://crates.io/crates/tokio) | dev-dependencies | minor | `1.14.0` -> `1.15.0` |
| [tokio](https://crates.io/crates/tokio) | dependencies | minor | `1.14.0` -> `1.15.0` |

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Author: bors

Cargo.lock

@@ -82,7 +82,7 @@ swirl = { git = "https://github.com/sgrif/swirl.git", rev = "e87cf37" }
 tar = "0.4.38"
 tempfile = "3"
 thiserror = "1.0.30"
-tokio = { version = "1.14.0", features = ["net", "signal", "io-std", "io-util", "rt-multi-thread", "macros"]}
+tokio = { version = "1.15.0", features = ["net", "signal", "io-std", "io-util", "rt-multi-thread", "macros"]}
 toml = "0.5"
 tracing = "0.1"
 tracing-subscriber = "0.2"
@@ -93,7 +93,7 @@ claim = "0.5"
 conduit-test = "0.10.0"
 hyper-tls = "0.5"
 lazy_static = "1.4"
-tokio = "1.14.0"
+tokio = "1.15.0"
 tower-service = "0.3.1"
 
 [build-dependencies]