Removed GNU licence and tidied imports

[jdha]

• [ ] Closes #11
• [x] Passes pre-commit run --all-files
• [x] Project, label, and assignee tabs are populated

[codecov-commenter]

Codecov Report

Merging #12 (5ce4273) into main (670f80a) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #12   +/-   ##
=======================================
  Coverage   60.00%   60.00%           
=======================================
  Files           1        1           
  Lines           5        5           
=======================================
  Hits            3        3           
  Misses          2        2           

Flag	Coverage Δ
unittests	60.00% <ø> (ø)

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