updater: Bump up the BBOTA version to 4.

To accommodate new changes in N release, such as error correction [1]
and other potential changes to the updater.

[1]: commit 0a7b47397db3648afe6f3aeb2abb175934c2cbca

Change-Id: I4dd44417d07dd0a31729894628635a0aa1659008
1 file changed