Fix Bug with Miner recieving messages in list of strings instead of list of dicts

[ViktorThink]

This PR fixes #1292

On the previous version of bittensor/_synapse/text_prompting/synapse.py (https://github.com/opentensor/bittensor/blob/eff272409704d801ce337a2ce850ba49368848d5/bittensor/_synapse/text_prompting/synapse.py)
On line 57 it is:

formatted_messages = [ json.loads(message) for message in forward_call.messages ]

The most recent update to the file made yesterday, had the json.loads function removed, causing the error:

self.formatted_messages = [ message for message in self.messages ]

So I simply added import of json and json loading the messages.

I will test the solution today to make doubly sure it solves the issue.

[ViktorThink]

I have tested now and it works correctly:

messages: [{'role': 'system', 'content': '\nYou are designed to assist with a wide range of tasks, from answering simple questions to providing in-depth explanations and discussions on a wide range of topics.\n'}, {'role': 'user', 'content': '\nAsk me a random question about anything. Make the question very domain specific. Do not include the answer in the question.\n'}]