🐛 [BUG] `InvalidVersion` in v0.6.0

[janosh]

Describe the bug

v0.6.0 is raising

packaging.version.InvalidVersion: Invalid version: ''

in atomate2 CI

stack trace

  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/atomate2/forcefields/md.py", line 333, in calculator
    return ase_calculator(self.force_field_name, **self.calculator_kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/atomate2/forcefields/utils.py", line 439, in ase_calculator
    calculator = NequIPCalculator.from_deployed_model(**kwargs)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/nequip/ase/nequip_calculator.py", line 62, in from_deployed_model
    model, metadata = nequip.scripts.deploy.load_deployed_model(
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/nequip/scripts/deploy.py", line 131, in load_deployed_model
    assert packaging.version.parse(
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/packaging/version.py", line 54, in parse
    return Version(version)
           ^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/packaging/version.py", line 200, in __init__
    raise InvalidVersion(f"Invalid version: '{version}'")
packaging.version.InvalidVersion: Invalid version: ''

To Reproduce

Expected behavior A clear and concise description of what you expected to happen.

Environment (please complete the following information):

• OS: Ubuntu
• python version: 3.9

Additional context

was fine before v0.6.0