Handle Date input

[Kalzem]

Thanks for the package.

My only issue is that it doesn't work well with zod Date input and gives me this error:

Error converting schema: 250 |         throw new Error("Function types cannot be represented in JSON Schema");
251 |     }
252 | };
253 | export const transformProcessor = (_schema, ctx, _json, _params) => {
254 |     if (ctx.unrepresentable === "throw") {
255 |         throw new Error("Transforms cannot be represented in JSON Schema");
                        ^
error: Transforms cannot be represented in JSON Schema

I guess this can be expected as dates are not jsonable by default, however the dates are usually sent as ISO formatted strings, so it would be nice for trpc-docs-generator to handle those inputs as strings.