cargo: bump stop-token from 0.2.0 to 0.4.0

Bumps [stop-token](https://github.com/async-rs/stop-token) from 0.2.0 to 0.4.0.
- [Release notes](https://github.com/async-rs/stop-token/releases)
- [Commits](https://github.com/async-rs/stop-token/commits)

---
updated-dependencies:
- dependency-name: stop-token
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Cargo.lock

@@ -65,7 +65,7 @@ serde = { version = "1.0", features = ["derive"] }
 sha-1 = "0.9"
 sha2 = "0.9"
 smallvec = "1"
-stop-token = "0.2"
+stop-token = "0.4"
 strum = "0.21"
 strum_macros = "0.21"
 surf = { version = "2.3", default-features = false, features = ["h1-client"] }