Remove unused dependencies

packages/py-spinnfrontendcommon/package.py

@@ -4,12 +4,10 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 from spack.package import *
-from spack.fetch_strategy import URLFetchStrategy
 from spack.store import find
 from llnl.util import tty
 from os import makedirs
 from urllib.request import urlretrieve
-import os
 
 
 _JAR_URL = "https://github.com/SpiNNakerManchester/JavaSpiNNaker/releases/download/7.0.0/spinnaker-exe.jar"