added semantic versioning and automated releases

[nicolasbisurgi]

Implemented the same release management than in RushTI and as discussed here

[onefloid]

Hi @nicolasbisurgi, grand job! I left a few comments in the code.

[Copilot]

Pull request overview

This pull request implements automated semantic versioning and nightly releases for TM1py, following the same approach used in the RushTI project. The changes migrate package configuration from setup.py to the modern pyproject.toml format and introduce GitHub Actions workflows for automated PR validation and nightly releases.

Changes:

• Migrated package metadata and dependencies from setup.py to pyproject.toml following PEP 621 standards
• Added automated PR validation workflow to check code formatting (Black) and linting (Ruff)
• Implemented nightly release workflow with semantic versioning based on PR labels (release:patch, release:minor, release:major)
• Updated version management to use importlib.metadata with fallback
• Comprehensive documentation updates for contributors and maintainers

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
setup.py	Simplified to minimal backwards-compatible setup, delegating configuration to pyproject.toml
pyproject.toml	New comprehensive package configuration with metadata, dependencies, and tool settings
TM1py/init.py	Updated version detection to read from installed package metadata with fallback
CONTRIBUTING.md	New top-level contributor guide redirecting to detailed documentation
docs/how-to-contribute.md	Extensively expanded with setup instructions, PR process, release workflow explanation
.github/RELEASE_LABELS_GUIDE.md	New maintainer guide for using release labels to control semantic versioning
.github/workflows/pr-validation.yml	New workflow for validating PRs with Black and Ruff checks
.github/workflows/nightly-release.yml	New comprehensive workflow for automated nightly releases with testing and PyPI publishing

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[MariusWirtz]

@nicolasbisurgi, please take a quick look through my changes before we merge

[nicolasbisurgi]

Reviewed the changes - looks good to merge! All feedback (from @onefloid and Copilot) has been addressed properly. The only minor nit left is the broad except Exception in init.py but I don't think we care much for that.
Thanks all!