Replacing deprecated call in `GnAnnotator.kt`

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[trespasserw]

Ouch. JB might have signed a corporate CLA, but finding it out it's too much of a hassle for such a trivial change :) Please feel free to close it and make the fix yourself. Thanks!

[brunowonka]

Sorry for ghosting on this, I haven't had time to work on the plugin lately. Thank you very much for the patch I'll turnaround a PR with the fix and then fix this (keeping this open in the meanwhile so I don't forget).

[brunowonka]

Closing this in favor of #17 and #18