message: fix: remove mergepoint from past migration
diff: """add_last_saved_at_to_slice_model
  Revision ID: 6d20ba9ecb33
  -Revises: ('ae1ed299413b', 'f6196627326f')
  +Revises: 'f6196627326f'
  Create Date: 2021-08-02 21:14:58.200438
  """
  # revision identifiers, used by Alembic.
  revision = "6d20ba9ecb33"
  -down_revision = ("ae1ed299413b", "f6196627326f")
  +down_revision = "f6196627326f"
  import sqlalchemy as sa
  from alembic import op
  