Adapt cli declaration entrypoint to swh.core 0.3

requirements-swh.txt

 # Add here internal Software Heritage dependencies, one per line.
+swh.core >= 0.3
 swh.model

setup.py

@@ -69,6 +69,6 @@ setup(
     },
     entry_points="""
         [swh.cli.subcommands]
-        auth=swh.web.client.cli:auth
+        auth=swh.web.client.cli
     """,
 )

swh/web/client/cli.py

@@ -7,11 +7,12 @@
 # control
 import click
 from click.core import Context
+from swh.core.cli import swh as swh_cli_group
 
 CONTEXT_SETTINGS = dict(help_option_names=["-h", "--help"])
 
 
-@click.group(name="auth", context_settings=CONTEXT_SETTINGS)
+@swh_cli_group.group(name="auth", context_settings=CONTEXT_SETTINGS)
 @click.option(
     "--oidc-server-url",
     "oidc_server_url",