Update Black to latest

[soininen]

There was a security vulnerability with the Black we were using.

Just reformatting. No functional changes intended.

Checklist before merging

• Documentation (also in Toolbox repo) is up-to-date
• Release notes have been updated
• Unit tests have been added/updated accordingly
• Code has been formatted by black & isort
• Unit tests pass

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.15%. Comparing base (ac9112c) to head (9a9bc0b).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
spinedb_api/db_mapping.py	0.00%	12 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #621   +/-   ##
=======================================
  Coverage   86.15%   86.15%           
=======================================
  Files          83       83           
  Lines       11475    11475           
  Branches     1636     1636           
=======================================
  Hits         9886     9886           
  Misses       1238     1238           
  Partials      351      351           

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