Adapt cli declaration entrypoint to swh.core 0.3

requirements-swh.txt

 # Add here internal Software Heritage dependencies, one per line.
-swh.core
+swh.core >= 0.3
 swh.model >= 0.3.8

setup.py

@@ -56,7 +56,7 @@ setup(
     include_package_data=True,
     entry_points="""
         [swh.cli.subcommands]
-        scanner=swh.scanner.cli:scanner
+        scanner=swh.scanner.cli
     """,
     classifiers=[
         "Programming Language :: Python :: 3",

swh/scanner/cli.py

@@ -11,7 +11,7 @@ from typing import Any, Dict
 import click
 
 from swh.core import config
-from swh.core.cli import CONTEXT_SETTINGS
+from swh.core.cli import CONTEXT_SETTINGS, swh as swh_cli_group
 
 # All generic config code should reside in swh.core.config
 DEFAULT_CONFIG_PATH = os.environ.get(
@@ -36,7 +36,7 @@ def parse_url(url):
     return url
 
 
-@click.group(name="scanner", context_settings=CONTEXT_SETTINGS)
+@swh_cli_group.group(name="scanner", context_settings=CONTEXT_SETTINGS)
 @click.option(
     "-C",
     "--config-file",