Encoding error on Windows

Setup ZerePy on Windows machine.

Run:
```
poetry install --no-root
poetry shell
poetry run python main.py
```

Observe error:
Could not load ZerePy agent
Error loading agent: 'charmap' codec can't decode byte 0x9d in position 2341: character maps to <undefined>

Resolve the issue by specifying encoding:
```
agent_dict = json.load(open(agent_path, "r", encoding='utf-8'))
```