ostree/container: add missing --version arg

https://pagure.io/pungi/pull-request/1726 tries to use
`self.args.version`, but the `pungi-make-ostree container`
subcommand does not actually have a `--version` arg, so that is
not going to work. This adds the required arg.

We *could* make it optional by still setting an empty update
dict if it's not specified, I guess, but not sure if that's worth
the effort.

Fixes: https://pagure.io/pungi/issue/1751

Signed-off-by: Adam Williamson <awilliam@redhat.com>
(cherry picked from commit 51d58322f2)

pungi/ostree/__init__.py

@@ -101,6 +101,13 @@ def main(args=None):
     container.add_argument(
         "--extra-config", metavar="FILE", help="JSON file contains extra configurations"
     )
+    container.add_argument(
+        "-v",
+        "--version",
+        metavar="VERSION",
+        required=True,
+        help="version identifier (required)",
+    )
 
     installerp = subparser.add_parser(
         "installer", help="Create an OSTree installer image"