build: Bump log from 0.4.17 to 0.4.20

Bumps [log](https://github.com/rust-lang/log) from 0.4.17 to 0.4.20.
- [Release notes](https://github.com/rust-lang/log/releases)
- [Changelog](https://github.com/rust-lang/log/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/log/compare/0.4.17...0.4.20)

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

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

vhost_user_block/Cargo.toml

@@ -11,7 +11,7 @@ block = { path = "../block" }
 env_logger = "0.10.0"
 epoll = "4.3.3"
 libc = "0.2.147"
-log = "0.4.17"
+log = "0.4.20"
 option_parser = { path = "../option_parser" }
 vhost = { version = "0.9.0", features = ["vhost-user-backend"] }
 vhost-user-backend = "0.11.0"