chore: downgrade vexflow to 1.2.93 again (#706)
there are still a few critical issues with the Vexflow 3x versions, see #706.
vexflow 1.2.93 has better measure layouting for measures with half notes.
also, there is no overlap of notes into the next measure.
tabs look better with 1.2.93 as well.
sschmid