chore(deps): bump tokio from 1.49.0 to 1.52.1 in /backend (#221)

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.49.0 to 1.52.1.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-1.49.0...tokio-1.52.1)

---
updated-dependencies:
- dependency-name: tokio
  dependency-version: 1.52.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/Cargo.lock

@@ -16,7 +16,7 @@
     "alloc",
     "raw_value",
   ] }
-  tokio = { version = "1.49.0", features = [ "macros", "rt-multi-thread" ] }
+  tokio = { version = "1.52.1", features = [ "macros", "rt-multi-thread" ] }
   toml = { version = "1.1.0" }
   tower-http = { version = "0.6", features = [ "cors" ] }
   tracing = { version = "0.1" }