Switch versioneer integration to build-time dependency mode

[Ulthran]

Summary

• remove the vendored versioneer helper in favor of build-time dependency mode
• declare versioneer[toml] as a build requirement so packaging can import Versioneer

Testing

• pytest

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https://chatgpt.com/codex/tasks/task_e_68f90c53560c8323a42629569bd1eb31

[Copilot]

Pull Request Overview

This PR migrates the project's version management from a hardcoded version string to dynamic versioning using Versioneer in build-time dependency mode. Instead of vendoring Versioneer's helper code, the project now declares versioneer[toml] as a build requirement and generates the _version.py file to compute version numbers from Git metadata.

Key changes:

• Replaced hardcoded version with dynamic Git-based versioning
• Added Versioneer configuration in pyproject.toml
• Generated _version.py for runtime version computation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/heyfastqlib/_version.py	Generated Versioneer module that computes version from Git metadata
src/heyfastqlib/init.py	Updated to import and use version from _version.py instead of hardcoded string
pyproject.toml	Added versioneer[toml] build dependency and Versioneer configuration
.gitattributes	Configured Git export-subst for _version.py to enable tarball versioning

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