We do not always release the tooling (mender-convert/Yocto) together with the top level releases.
The regexp fix was integrated here, https://github.com/mendersoftware/grub-mender-grubenv/commit/9f1621b2f791a7f6a2b0faf37e932d0f3c5507ed. This component is not versioned anymore, that we do not do releases of it and just base it on git revision.
But, above should be included in upcoming release of mender-convert, currently in beta, https://github.com/mendersoftware/mender-convert/releases/tag/2.1.0b1, you can see the revision here.