fix: cap tokio-util below 0.7.20 to keep the 1.83 MSRV

[ChiragAgg5k]

The 0.16.0 publish to crates.io failed because tokio-util 0.7.20, pulled in through tokio/reqwest, requires rustc 1.85, while the crate declares rust-version = "1.83" and the publish workflow builds with 1.83: https://github.com/appwrite/sdk-for-rust/actions/workflows/publish.yml

This caps it below 0.7.20, the same way hyper-util, indexmap and url are already capped. cargo +1.83.0 test --all-features passes (750 tests) and cargo publish --dry-run succeeds with a fresh lockfile.

0.16.0 is not on crates.io yet, so once this merges the publish workflow can be run from main to publish 0.16.0.

Related: appwrite/sdk-generator#2002

[hansi-codes]

🟢 Tier S · Ready to merge

The change is a focused dependency constraint with no identified behavior or compatibility issue.

Adds a direct tokio-util version constraint capped below 0.7.20. This keeps dependency resolution within the Rust 1.83 compatibility range described in the PR.

Verdict	New comments	Fixed	Still open
✅ Approved	0	0	0

📂 Walkthrough · 1

File	Change
Cargo.toml	Adds the tokio-util version cap.

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[hansi-codes]

🟢 Tier S · Looks good to merge. Summary