chore(deps): upgrade to Python 3.12 and prepare for 0.6.0 release

- Update Docker base image to Python 3.12-slim-bookworm
- Bump version from 0.6.0rc1 to 0.6.0
- Update documentation to reflect release version changes
- Fix license specification in pyproject.toml and setup.py
- Clean up code formatting in demo_docker_api.py

BREAKING CHANGE: Base Python version upgraded from 3.10 to 3.12

docs/examples/docker/demo_docker_api.py

@@ -398,7 +398,6 @@ async def demo_param_js_execution(client: httpx.AsyncClient):
     elif results:
          console.print("[yellow]JS Execution Result not found in response.[/]")
 
-
 async def demo_param_screenshot(client: httpx.AsyncClient):
     payload = {
         "urls": [SIMPLE_URL],
@@ -430,8 +429,6 @@ async def demo_param_ssl_fetch(client: httpx.AsyncClient):
     elif results:
          console.print("[yellow]SSL Certificate data not found in response.[/]")
 
-
-
 async def demo_param_proxy(client: httpx.AsyncClient):
     proxy_params_list = load_proxies_from_env() # Get the list of parameter dicts
     if not proxy_params_list: