with Debian dir a21bc9196b874697507e45ed0c1f9394ddcf7bb3

Loaders use it, but it is ignored by the pg storage.
However, as the Cassandra storage uses swh-model to validate
its input, it refuses this input from the loaders (and journal).

Remove version checking code, pyblake2 is installed by default on python 3.6+

with Debian dir d6285282d0519bd3c16e020b63d01f4265c3da97

This is a fix to workaround pip's inability to correctly solve
extra requirements (swh-model depends on swh-core[], but if other
packages depend on swh-model and swh-core[http], the 'http' extra
does not always get installed).

with Debian dir ddca98e6157d1ca6e603aae3d7e3f42f298e9ce3

pgsql does not support it.

There is more repetition, but it's easier to read and
'%timeit Revision.from_dict(d)' is 5 times faster.

with Debian dir c894ded2e79935c359c08677b4cfae26055af536

with Debian dir ce2af20bf36b866aa94bee987331fb01bc54281f

with Debian dir 7bbed261a46ff1eeb75569460b5bd19663b2664d

with Debian dir 8c463e5b82a879fb29dc4dcca6d0c1118906875d