feat: SDK update for version 0.16.0

[ChiragAgg5k]

This PR contains updates to the SDK for version 0.16.0.

What's Changed

• Breaking: functions.create and functions.update take a new optional interval argument; pass None to keep the current behaviour
• Added: interval on the Function model and functions_interval_minimum on the BillingPlan model

[hansi-codes]

🟢 Tier S · Ready to merge

No actionable defects found in the reviewed changes.

Updates the Rust SDK package and reported client version to 0.16.0. Adds function schedule intervals to the Functions create/update requests and Function model, and exposes the minimum allowed function interval on BillingPlan. Updates the corresponding function examples and release references.

Verdict	New comments	Fixed	Still open
✅ Approved	0	0	0

📂 Walkthrough · 10

File	Change
CHANGELOG.md	Updates the changelog release heading and tag URL to 0.16.0.
Cargo.toml	Bumps the crate version to 0.16.0.
README.md	Updates the dependency example to use version 0.16.0.
docs/examples/functions/create.md	Adds the optional interval argument to the function creation example.
docs/examples/functions/update.md	Adds the optional interval argument to the function update example.
src/client.rs	Updates the user-agent and SDK version headers to 0.16.0.
src/lib.rs	Updates the documented dependency version and public SDK VERSION constant.
src/models/billing_plan.rs	Adds the minimum allowed function schedule interval field and getter.
src/models/function.rs	Adds the optional interval field, getter, and setter to Function.
src/services/functions.rs	Adds optional interval parameters to function creation and update requests.

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[hansi-codes]

🟢 Tier S · Looks good to merge. Summary