[sonic-ztp] submodule update (sonic-net#7984)

Advance submodule update with the following changes:
4475750 Config reload fix (sonic-net#29)
cf60d5e [ci]: add proper azp (sonic-net#26)
f0fbfe7 [CI] Set up CI with Azure Pipelines (sonic-net#25)
879d7bd Include port default fec configuration to be included in ZTP configuration (sonic-net#24)
a6ae955 Add a pre-defined plugin to download a list of files (sonic-net#23)
6f0305b [MultiDB] Add multidb support to sonic-ztp (sonic-net#16)