Breaking changes in gsd 3.0

[chrisjonesBSU]

GSD 3.0 was recently released, and how some breaking changes in its API. It moves away from the Snapshot terminology and instead uses Frame

Example:

>>> import gsd.hoomd
>>> snap = gsd.hoomd.Snapshot
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'gsd.hoomd' has no attribute 'Snapshot'
>>> frame = gsd.hoomd.Frame
>>>

This causes some issues in convert_hoomd. I changed the version pinning for GSD in #737 as the tests were failing, but we'll still have to make some changes to support both gsd 2 and gsd 3.

[chrisjonesBSU]

I have a PR ready to go that adds some checks to io.py and convert_hoomd that supports both gsd 2.0 and 3.0.

I'm curious though what others think is the best way to proceed. gsd.hoomd.Frame is introduced in gsd 2.8 So, we could update convert_hoomd to use Frame and still technically support both major versions with gsd >= 2.8

[daico007]

If they (gsd.hoomd.Frame and gsd.hoomd.Snapshot) is doing the same thing, my vote is to update all the syntax to work with gsd.hoomd.Frame and pin gsd to be >2.8

[CalCraven]

I would second the adoption of gsd.hoomd.Frame, and pinning to >2.8.