Update astrocyte to 0.3.1

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PR checklist

• This comment contains a description of changes (with reason)
• If you've fixed a bug or added code that should be tested, add tests!
• CHANGELOG.md is updated

Closes #84 (closed)

changed milestone to %2.0.0

added documentation enhancement labels

merged

mentioned in commit 27540804

Closed #86 (closed)