Remove explicit setting of the task base class

since it's now the default base class in swh-scheduler (>= 0.0.39)

swh/lister/pypi/tasks.py

@@ -2,14 +2,13 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from swh.scheduler.task import SWHTask
 from swh.scheduler.celery_backend.config import app
 
 from .lister import PyPILister
 
 
 @app.task(name='swh.lister.pypi.tasks.PyPIListerTask',
-          base=SWHTask, bind=True)
+          bind=True)
 def pypi_lister(self, **lister_args):
     self.log.debug('%s(), lister_args=%s' % (
         self.name, lister_args))
@@ -18,7 +17,7 @@ def pypi_lister(self, **lister_args):
 
 
 @app.task(name='swh.lister.pypi.tasks.ping',
-          base=SWHTask, bind=True)
+          bind=True)
 def ping(self):
     self.log.debug(self.name)
     return 'OK'