Allow a higher number of workers in the mock_api

This is because a higher number of component streams are required for
testing some scenarios in the logical meter formula generation and
composition.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

tests/microgrid/mock_api.py

@@ -262,7 +262,7 @@ def __init__(
         self, servicer: MicrogridServicer, host: str = "[::]", port: int = 61060
     ) -> None:
         """Create a MockGrpcServicer instance."""
-        self._server = grpc.aio.server(futures.ThreadPoolExecutor(max_workers=10))
+        self._server = grpc.aio.server(futures.ThreadPoolExecutor(max_workers=20))
         add_MicrogridServicer_to_server(servicer, self._server)
         self._server.add_insecure_port(f"{host}:{port}")