prepare v0.3.0 release

[leifdenby]

Describe your changes

Updates CHANGELOG and pyproject.toml to reference the new v0.3.0 release that will be tagged shortly.

Issue Link

No issue

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📖 Documentation (Addition or improvements to documentation)

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• My branch is up-to-date with the target branch - if not update your fork with the changes from the target branch (use pull with --rebase option if possible).
• I have performed a self-review of my code
• For any new/modified functions/classes I have added docstrings that clearly describe its purpose, expected inputs and returned values
• I have placed in-line comments to clarify the intent of any hard-to-understand passages of my code
• I have updated the README to cover introduced code changes
• I have added tests that prove my fix is effective or that my feature works
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Each PR comes with its own improvements and flaws. The reviewer should check the following:

• the code is readable
• the code is well tested
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• I have added a line to the CHANGELOG describing this change, in a section
  reflecting type of change (add section where missing):
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  • changed: when default behaviour of the code has been changed
  • fixes: when your contribution fixes a bug

Checklist for assignee

• PR is up to date with the base branch
• the tests pass
• author has added an entry to the changelog (and designated the change as added, changed or fixed)
• Once the PR is ready to be merged, squash commits and merge the PR.

[joeloskarsson]

One small typo, then all good to go 😄

[leifdenby]

In setting things up on Gefion I just noticed that neural-lam doesn't currently expose its own version. It is common to use the <module>.__version__ attribute to do this, as in I would expect the following to work:

import neural_lam
print(neural_lam.__version__)

Since we use pyproject.toml and require python>=3.9 (importlib.metadata is in the standard library as of python3.8, https://docs.python.org/3/library/importlib.metadata.html) we can use importlib.metadata by adding the following to neural_lam/__init__.py:

import importlib.metadata

try:
    __version__ = importlib.metadata.version(__name__)
except importlib.metadata.PackageNotFoundError:
    __version__ = "unknown"

The exception handling is for when the package is a local copy or hasn't been installed with setuptools (i.e. pip or pdm install). Xarray uses the same approch https://github.com/pydata/xarray/blob/main/xarray/__init__.py#L60

Would you be ok with me including this in this PR? It would help our tracking of what is installed when using neural-lam on Gefion

[joeloskarsson]

Yes, that would be good to add. I am ok with you just adding that in this PR.