chore: add --version flag to support version check

Signed-off-by: Gang Li <[email protected]>

charon/cmd/__init__.py

@@ -13,7 +13,7 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
-from click import group
+from click import group, version_option, pass_context
 from charon.cmd.cmd_upload import upload
 from charon.cmd.cmd_delete import delete
 from charon.cmd.cmd_index import index
@@ -22,7 +22,9 @@
 
 
 @group()
-def cli():
+@version_option()
+@pass_context
+def cli(ctx):
     """Charon is a tool to synchronize several types of
        artifacts repository data to Red Hat Ronda
        service (maven.repository.redhat.com).