Don't import pyarrow just to check version

[martindurant]

We would rather not import pyarrow, since from v2.0.0, we don't use it anyway.

Ref #411

cc @jorisvandenbossche - this is the chain of version checks that we talked about in your PR.

[ ] %time import fsspec
93 ms (this branch)
183 ms (master)

[jorisvandenbossche]

Looks good!