Amendments for R_SP_LM.V and R_SP_LN.VIII take "year" as position_on, not a full date

[ronaldtse]

They should be:

  - type: amendment
    target:
      publication: R_SP_LN.VIII
      position_on: 2016

And

  - type: amendment
    target:
      publication: R_SP_LM.V
      position_on: 2019

But since ituob.org currently does not support position_on: being a year, we temporarily changed these into full dates, i.e. January 1 of that year.

This task is to revert those changes once ituob.org supports them.