Bump tokio from 1.21.1 to 1.21.2 (#436)

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.21.1 to 1.21.2.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/compare/tokio-1.21.1...tokio-1.21.2)

---
updated-dependencies:
- dependency-name: tokio
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Cargo.lock

@@ -2014,9 +2014,9 @@ checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
 
 [[package]]
 name = "tokio"
-version = "1.21.1"
+version = "1.21.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0020c875007ad96677dcc890298f4b942882c5d4eb7cc8f439fc3bf813dc9c95"
+checksum = "a9e03c497dc955702ba729190dc4aac6f2a0ce97f913e5b1b5912fc5039d9099"
 dependencies = [
  "autocfg",
  "bytes",
@@ -2024,7 +2024,6 @@ dependencies = [
  "memchr",
  "mio",
  "num_cpus",
- "once_cell",
  "pin-project-lite",
  "signal-hook-registry",
  "socket2",