feat: add auto lint fix CI workflow

[saber04414]

Auto lint fix in CI

Description

This PR adds an automated CI workflow that automatically fixes linting issues and commits them back to pull request branches. This saves developers time by eliminating the need to manually fix formatting issues.

Changes

• Added format target to Makefile: New target that runs black and nbqa black to auto-fix Python code and Jupyter notebook formatting
• Created GitHub Actions workflow (.github/workflows/lint_fix.yml):
  • Triggers on pull requests to main branch
  • Checks out the PR branch
  • Installs dependencies via make dev
  • Runs make format to auto-fix linting issues
  • Automatically commits and pushes fixes back to the PR branch

How it works

1. When a PR is opened or updated, the workflow runs
2. It formats code using Black (Python) and nbqa (notebooks)
3. If any changes are detected, they are automatically committed with message "🤖 Auto-fix linting issues"
4. Changes are pushed back to the PR branch

Testing

• ✅ Verified Makefile format target syntax
• ✅ Tested Black formatter functionality
• ✅ Validated workflow YAML structure
• ✅ Confirmed workflow file follows existing patterns

Related Issue

Closes #2060

Notes

• The workflow uses GITHUB_TOKEN for authentication (automatically provided by GitHub Actions)
• Only runs on pull requests to main branch
• Uses concurrency control to prevent multiple runs
• Follows the same pattern as existing workflows in the repository

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Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=157775043

[saber04414]

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[saber04414]

@SunsetWolf Could you please review my pr?