Remove unused imports

Author: vkarak

reframe/frontend/reporting/__init__.py

@@ -17,14 +17,12 @@
 import time
 import uuid
 from collections import UserDict
-from collections.abc import Hashable
 
 import reframe as rfm
 import reframe.utility.jsonext as jsonext
 import reframe.utility.osext as osext
 from reframe.core.exceptions import ReframeError, what, is_severe, reraise_as
 from reframe.core.logging import getlogger, _format_time_rfc3339, time_function
-from reframe.core.runtime import runtime
 from reframe.core.warnings import suppress_deprecations
 from reframe.utility import nodelist_abbrev, OrderedSet
 from .storage import StorageBackend