matrixsynapse: Conffile prompt during upgrade

Setting up matrix-synapse (0.33.4-1) ...

Configuration file '/etc/matrix-synapse/homeserver.yaml'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.

This file was recently changed here: matrix-team/matrix-synapse@0238061a