Drop support for Python 3.6

[redeboer]

It is becoming increasingly bothersome to support Python 3.6. This issue keeps track of arguments for dropping support:

• Postponed evaluation of annotations (PEP 563)
• Simplified union type notation (if using from __future__ import annotations).
• refactor!: generalize STG to MutableTransition qrules#156 (comment)
• drop Python 3.6 support zfit/phasespace#69 (comment)
• Abbreviate type aliases in API policy#59
• SymPy is not tested on Python 3.6 anymore. See SymPy v1.10 and SymPy version support policy.

Useful tools

• pyupgrade
• flake8-future-annotations

See also

• What’s New In Python 3.7
• Scikit-HEP's Statement on Python 3.6

Progress

Preview Give feedback

1. BREAK: drop support for Python 3.6 qrules#250
   ⚠️ Interface 🖱️ DX +2
   
2. refactor: adapt to SymPy v1.10 and drop Python 3.6 ampform#249
   ⚠️ Interface +1
   
3. build!: drop Python 3.6 support tensorwaves#431
   🔨 Maintenance +1
   
4. build: drop support for Python 3.6 compwa-org#132
   🔨 Maintenance 🖱️ DX +2
   
5. DX!: switch to Ruff as linter PWA-pages#189
   🔨 Maintenance +1
   
6. DX: drop Python 3.6 support repo-maintenance#234
   ⚠️ Interface 🖱️ DX +2
   

[redeboer]

Group meeting decision 25.02.2022: drop support once new problems appear.

[redeboer]

Already fixed by ComPWA/qrules#250