Update the minimum cython version in setup.py

[jbarnoud]

See discussion at #3527 (comment)

The minimum version of cython set in setup.py is older than the minimum supported by numpy.

This may be related to #3526 from @tylerjereddy and is a follow up to #3527.

[orbeckst]

FYI, there's the experimental PR #2989 for Cython 3.x

[IAlibay]

So by default when we build MDA for release I usually create a fresh environment with the latest stable version of Cython. Unless there are backwards compatibility issues maybe we should tighten it up to 0.29+?

Maybe we can just go ahead and say we'll deal with that in 2.2.0 when hopefully 0.30 gets released though? (after which we just say 0.3+ since there's massive compatibility changes?)