Add ability to mark function outputs as unserializable

[skrawcz]

Is your feature request related to a problem? Please describe.
In Parallel & Collect blocks, there could be a process boundary. Inputs that are invariant to each chunk of the block need to be serialized and deserialized -- but for things like clients (e.g. openai, db client) those objects aren't serializable and things break.

Describe the solution you'd like

@unserializable
def client() -> object:
   """Some client, e.g. openai, etc"""
   return ... 

Then Hamilton will know that for each parallel block, we rerun this function, versus trying to run it once and trying to serialize and deserialize it.

Describe alternatives you've considered
You can get around this by making the client() function depend on some part of the parallel block (client(some_dep: object)) thereby forcing it to be run each block.

Additional context
This would be a quality of life improvement.

[elijahbenizzy]

Similar to this: #90

[skrawcz]

Another alternative is to create a wrapper object and use that instead:

class SerializeableOpenAIClient:
    def __init__(self):
        self.client = OpenAI()

    def __getstate__(self):
        return {}

    def __setstate__(self, d):
        self.client = OpenAI()

def client() -> SerializeableOpenAIClient:
    return SerializeableOpenAIClient()