fixes #852: do not pass --ipam-driver option when value set to default

podman returns _unsupported ipam driver "default"_ when `--imap-driver
default` parameter is passed.

So, when ipam driver is set to "default" in docker-compose.yml, --imap-driver
must not be used when podman is called.

podman_compose.py

@@ -762,7 +762,7 @@ async def assert_cnt_nets(compose, cnt):
                 args.extend(("--opt", f"{key}={value}"))
             ipam = net_desc.get("ipam", None) or {}
             ipam_driver = ipam.get("driver", None)
-            if ipam_driver:
+            if ipam_driver and ipam_driver not in ("default"):
                 args.extend(("--ipam-driver", ipam_driver))
             ipam_config_ls = ipam.get("config", None) or []
             if is_dict(ipam_config_ls):