Backport versioned orderable rows fix

[NightJar]

#243 fixed an issue with SilverStripe 4's updated Versioned API and publishing changes to re-ordered rows, however the current master branch is for the 4.x release line, and the bug is still present in the 3.x release line. The fix is somewhat trivial, and needs to be backported to prevent issues arising within other modules which rely on this functionality (and have a requirement of e.g. ^3 - e.g. silverstripe/silverstripe-elemental#177).

[robbieaverill]

Released as 3.1.1: https://github.com/symbiote/silverstripe-gridfieldextensions/releases/tag/3.1.1