Bump darling from 0.20.6 to 0.20.7 in /lang/rust (#2763)

Bumps [darling](https://github.com/TedDriggs/darling) from 0.20.6 to 0.20.7.
- [Release notes](https://github.com/TedDriggs/darling/releases)
- [Changelog](https://github.com/TedDriggs/darling/blob/master/CHANGELOG.md)
- [Commits](TedDriggs/darling@v0.20.6...v0.20.7)

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

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

Author: dependabot[bot]

lang/rust/Cargo.lock

@@ -33,7 +33,7 @@ readme = "README.md"
 proc-macro = true
 
 [dependencies]
-darling = { default-features = false, version = "0.20.6" }
+darling = { default-features = false, version = "0.20.7" }
 proc-macro2 = { default-features = false, version = "1.0.78" }
 quote = { default-features = false, version = "1.0.35" }
 serde_json = { workspace = true }