This came up in the maintenance meeting and then again in #7345 (review) so I thought we can finish the conversation here.

@crusaderky mentioned how xarray handles this:

At xarray and pint we use a rolling policy based on NEP-29:
https://xarray.pydata.org/en/stable/installing.html#minimum-dependency-versions
The number of months listed is arbitrary and subject to negotiation. The key benefit of such a policy is that it allows developer to bump up minimum dependencies as needed, without initiating a discussion every time.

@pentschev suggested that we use only packages released in the last 18 months to match NEP-29.

Ping @jakirkham @jrbourbeau @dask/maintenance