chore: release 0.3.0

[github-actions[bot]]

:robot: I have created a release *beep* *boop*

0.3.0 (2020-12-19)

Features

• making the nn search more robust (37fbf07)

Miscellaneous

• added test for metal ordering, #36 (4b638b8)
• added test for number of atoms #32 (13d945f)
• added test for the xyz file (b7e89f4)
• adding tests (2789164)
• cleanup, removing unused modules (a5b74f2)
• cleanup, removing unused modules (ffa42a2)
• excluding test dir #37 (b972c7a)
• excluding test package/dir (49a0fae)
• linting (8061393)
• linting (bbe7cb1)

• updated version classifier, updated author list (5b48f12)

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