Specify mongo replica set protocolVersion. (#6468)
Specify mongo replica set protocolVersion. (#6468)

Mongo 4 no longer supports protocolVersion 0, so we need to explicitly specify protocolVersion: 1.
arbrandes/edx-configuration,edx/configuration,mitodl/configuration,mitodl/configuration,edx/configuration,arbrandes/edx-configuration,arbrandes/edx-configuration,arbrandes/edx-configuration,mitodl/configuration,edx/configuration,edx/configuration,arbrandes/edx-configuration,mitodl/configuration