Support exactOptionalPropertyTypes flag

[VanCoding]

Hi and thanks a lot for this awesome library!

Today I wanted to switch on the TypeScript option "exactOptionalPropertyTypes" for a project and noticed that the generated Zeus client doesn't like it. So I decided to fix it by myself quickly and make a PR. And here it is now :)

What I wasn't sure about was the example-code. When I generate it, I get a different schema and a therefore a different client.

Let me know if I missed something or if there's anything else I should do before you can merge it.

Best regards and thanks again, Patrik

[VanCoding]

@aexol Any way to the this merged in?