1.2.1

Added, because the documentation promised it

Withdraw accessibility exemption, on an asset, one or many. The
documentation described withdrawal from the first release and there was no way
to do it: the column existed, active() filtered on it, and nothing in the
control panel ever set it. An exemption was permanent once granted.

The row is not deleted. It records who ended it and when, and an
already-withdrawn exemption is left alone rather than re-stamped, so the time
in the record is the time somebody decided. The action appears only where there
is an active exemption to withdraw.

Fixed, where an upgrade did not arrive

docs:install now applies migrations added after the tables were created.
It returned early on "the tables exist", so a column added in a later release
never reached a site that installed an earlier one. Run it after upgrading; it
reports "already installed" when there is nothing to do.

Upgrading re-checks nothing.