Introduce Python v3.11 support

• Remove runners tags
• Introduce tests:3.11 job
• Based Silkaj container on v3.11 container
• Move coverage from tests:3.9:cov to tests:3.11:cov job
• Set default PYTHON_VERSION to 3.11
• Bump pre-commit hooks versions
• pyproject.toml: Create test group
• Bump pytest-cov to v4

Close #442 (closed).