re-export codecjson type

Author: d-v-b

src/zarr/abc/codec.py

@@ -5,7 +5,10 @@
 
 from zarr.abc.metadata import Metadata
 from zarr.core.buffer import Buffer, NDBuffer
-from zarr.core.common import concurrent_map
+from zarr.core.common import (  # noqa: F401 CodecJSON re-exported for backwards compatibility
+    CodecJSON_V2,
+    concurrent_map,
+)
 from zarr.core.config import config
 
 if TYPE_CHECKING: