pycriu: use explicit imports for __init__

_init__.py defines the public API for pycriu. It is important to use
explicit imports to avoid leaking every symbol from criu.py into the
pycriu namespace. This avoids import-time side effects, prevents name
collisions, and circular-import traps.

Fixes the following lint error:
  F403 `from .criu import *` used; unable to detect undefined names

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

Makefile

@@ -452,6 +452,8 @@ ruff:
 		test/inhfd/*.py \
 		test/others/rpc/config_file.py \
 		test/others/action-script/check_actions.py \
+		lib/pycriu/criu.py \
+		lib/pycriu/__init__.py \
 		lib/pycriu/images/pb2dict.py \
 		lib/pycriu/images/images.py \
 		scripts/criu-ns \

lib/pycriu/__init__.py

@@ -1,4 +1,15 @@
 from . import rpc_pb2 as rpc
 from . import images
-from .criu import *
-from .version import __version__
+from .criu import criu, CRIUExceptionExternal, CRIUException
+from .criu import CR_DEFAULT_SERVICE_ADDRESS
+from .version import __version__
+
+__all__ = (
+    "rpc",
+    "images",
+    "criu",
+    "CRIUExceptionExternal",
+    "CRIUException",
+    "CR_DEFAULT_SERVICE_ADDRESS",
+    "__version__",
+)