We moved those packages a little while ago, to avoid conflict with other top-level modules, particularly on the Uplink (we made an announcement post a few months ago, although the uplink was a little slower to update). The original names (eg import tables) still work for now, on the server and in older versions of the uplink, but we recommend moving to the anvil.* namespace (eg import anvil.tables).
If you upgrade to the latest version of the uplink, you’ll find that import anvil.tables works:
pip install --upgrade anvil-uplink