build: bump clap from 3.2.20 to 3.2.21

Bumps [clap](https://github.com/clap-rs/clap) from 3.2.20 to 3.2.21.
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/v3.2.21/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/v3.2.20...v3.2.21)

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

Signed-off-by: dependabot[bot] <support@github.com>

vhost_user_net/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["The Cloud Hypervisor Authors"]
 edition = "2021"
 
 [dependencies]
-clap = { version = "3.2.20", features = ["wrap_help","cargo"] }
+clap = { version = "3.2.21", features = ["wrap_help","cargo"] }
 env_logger = "0.9.0"
 epoll = "4.3.1"
 libc = "0.2.132"
@@ -19,4 +19,4 @@ vm-memory = "0.8.0"
 vmm-sys-util = "0.10.0"
 
 [build-dependencies]
-clap = { version = "3.2.20", features = ["cargo"] }
+clap = { version = "3.2.21", features = ["cargo"] }