Bump serde_json from 1.0.121 to 1.0.122 in /backend

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.121 to 1.0.122.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](serde-rs/json@v1.0.121...v1.0.122)

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

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

backend/Cargo.toml

@@ -24,7 +24,7 @@ reqwest = { version = "0.12.5", default-features = false, features = [
     "rustls-tls",
 ] }
 serde = { version = "1.0.204", features = ["derive"] }
-serde_json = { version = "1.0.120", features = ["raw_value"] }
+serde_json = { version = "1.0.122", features = ["raw_value"] }
 sqlx = { version = "0.8.0", features = [
     "runtime-tokio-rustls",
     "postgres",