[sonic-ztp] submodule update (#7984)

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