MVIC sample ballots now include proposals under Nonpartisan Section

[jacebrowning]

Example: https://mvic.sos.state.mi.us/Voter/GetMvicBallot/4321/698/

This seems odd since all proposals are nonpartisan.

https://github.com/citizenlabsgr/elections-api/pull/340 is a temporary workaround but maybe there is a better way to handle this.