Addresses breaking change in core pyworker (#22)

* Addresses breaking change in test_utils.py

Endpoint.get_endpoint_api_key() now requires instance

Moves the call to this function out of the APIClient and into main

* Ensure make_benchmark_payload has a value to calculate the workload

---------

Co-authored-by: Nader Arbabian <nader@vast.ai>

lib/server.py

@@ -27,7 +27,7 @@ def start_server(backend: Backend, routes: List[web.RouteDef], **kwargs):
         log.debug("starting server...")
         app = web.Application()
         app.add_routes(routes)
-        runner = web.AppRunner(app, handler_cancellation=True)
+        runner = web.AppRunner(app)
         await runner.setup()
         site = web.TCPSite(
             runner,