Define how core-members may be removed when they become inactive

[jhamman]

The core-developer guide describes how to add new core developers but fails to address what to do when members become inactive.

governance/CORE_DEV_GUIDE.md

Lines 157 to 169 in b1c414c

	## Inviting New Core Members
	Any core member may nominate other contributors to join the core team.
	While there is no hard-and-fast rule about who can be nominated, ideally,
	they should have: been part of the project for at least two months, contributed
	significant changes of their own, contributed to the discussion and
	review of others' work, and collaborated in a way befitting our
	community values. After nomination voting will happen on a private mailing list.
	While it is expected that most votes will be unanimous, a two-thirds majority of
	the cast votes is enough.
	Core developers can choose to become emeritus core developers and suspend
	their approval and voting rights until they become active again.

I would like to suggest some kind of trigger by which fully-inactive members can be removed from the core-developer roster of zarr projects. An example could be:

If a Core Developer becomes inactive in The Project for a period of one year, they will be considered for removal from the Project Core Developer Team.

cc @zarr-developers/python-core-devs, @zarr-developers/steering-council

xref: zarr-developers/zarr-python#1608

[rabernat]

Sounds good to me! Every open source project needs a mechanism to rotate inactive developers off.