Include shape in array types

Using [nptyping and beartype](https://github.com/ramonhagenaars/nptyping/blob/master/USERDOCS.md#Quickstart) we can pin down the dimensions that we accept. For instance, the constructor of `ValuationResult` can only accept 1D arrays but we don't enforce that.

Alternatively, [jaxtyping](https://github.com/patrick-kidger/jaxtyping) supports jax, torch and numpy in one go. But python 3.9 is required so we'd have to wait until EOL for 3.8 at the very least.

Are there any other libraries?