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

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