chore: ensure that no new clippy warnings are introduced via pr's

[flamestro]

What changed

• we now have a check in the pr workflow that checks if new clippy warnings are introduced and fails if they are.

Why

• we should avoid clippy warnings

User-facing impact

• more streamlined engineering process for contributors

Validation

• cargo check --locked
• Manual testing completed (if applicable)

Checklist

• PR is focused and scoped to one change
• Docs updated when behavior changes
• Breaking changes called out (if any)