chore(deps): update loom requirement from 0.6 to 0.7

Updates the requirements on [loom](https://github.com/tokio-rs/loom) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/loom/releases)
- [Changelog](https://github.com/tokio-rs/loom/blob/master/CHANGELOG.md)
- [Commits](tokio-rs/loom@v0.6.0...v0.7.0)

---
updated-dependencies:
- dependency-name: loom
  dependency-type: direct:production
...

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

Cargo.toml

@@ -17,7 +17,7 @@ serde = { version = "1.0", optional = true }
 [dev-dependencies]
 criterion = "0.5"
 futures = "0.3"
-loom = "0.6"
+loom = "0.7"
 proptest = "1.2"
 rand = "0.8"
 serde_test = "1.0"