Drop Python v3.7 support

Date when Python project won’t support v3.7

• Python 3.7 support will be dropped in June 27th of 2023 [1]
• Platform which still uses Py3.7

Todos

DuniterPy

• Drop Python v3.7 support (duniterpy#193 - closed)

Silkaj

• pyproject.toml: Bump minimum versions:
  • tools.poetry.dependency.python
  • tools.ruff.target-version
• Delete test job for v3.7 from .gitlab-ci.yml

Container

• Remove v3.7 Docker image generation. Drop Py3.7 image generation (docker/python3/poetry#9 - closed)

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• Create ticket for dropping Python 3.8 support: Drop Python v3.8 support (#464 - closed)