Don't use md5 to calculate objectid

[daviddavis]

md5 has a lot of limitations. See this commit in pymongo on a possible replacement:

mongodb/mongo-python-driver@6185035

[amcgregor]

The sheer volume of reduction happening means that choice of hash is essentially irrelevant, though I'm pleased to see choice of a hash that actually fits as a proposal. Collisions will occur. Because this isn't being used as a data integrity mechanism, this is (for the most part) perfectly acceptable. It's just a pseudo-distinct hardware identifier. [Edited to add:] it's sufficiently distinct when combined with hardware management logs, e.g. a duplicate HWID would likely not happen simultaneously.

The ultimate approach to making this component distinct would be to give the developer control over it. E.g. allow them to explicitly identify the "current machine" for their own internal management. (Unfortunately, my own actual hardware IDs are 128-bit UUIDs…)