setup: register the worker task in the swh.workers entrypoint

setup.py

@@ -58,6 +58,8 @@ setup(
         swh-deposit=swh.deposit.cli:main
         [swh.cli.subcommands]
         deposit=swh.deposit.cli:deposit
+        [swh.workers]
+        deposit.worker=swh.deposit.loader:register
     ''',
     classifiers=[
         "Programming Language :: Python :: 3",

swh/deposit/loader/__init__.py

+# Copyright (C) 2019 the Software Heritage developers
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+
+def register():
+    return {'task_modules': ['%s.tasks' % __name__]}