Add Zod v4 (beta)

[colinhacks]

• Add Zod 4 test case

Description

Adding a test case for Zod 4. The beta period for Zod may be a while and the full transition from Zod 3 -> Zod 4 will be far longer, so I figured it might make sense to include both during the transitionary period.

Testing

Added zod4 test case. Used a npm: prefix to install v3 and v4 simultaneously. Running the Zod 4 benchmark succeeds.

Checklist

• Conducted a self-review of the code changes.
• Updated documentation, if necessary.
• Added tests to validate the functionality or fix.

[DarkGL]

Please add zod4 to

https://github.com/moltar/typescript-runtime-type-benchmarks/blob/master/cases/index.ts

and import in

https://github.com/moltar/typescript-runtime-type-benchmarks/blob/master/test/benchmarks.test.ts

[colinhacks]

Added to benchmarks.test.ts. It was already added to cases/index.ts. Let me know if there's anything else 👍