Update package manager to uv, gh-workflow and bugfix

[FedericaBrando]

This PR includes several updates to the OpenVariant project, focusing on improving the build system, updating dependencies, and refining code quality. The changes include modifying the GitHub Actions workflow, updating the ReadTheDocs configuration and adopting a new build system configuration - which exploits hatchling and uv.

Build System and Configuration Updates:

• .github/workflows/openvariant_tester.yml: Updated the GitHub Actions workflow to use newer versions of actions, set up environment variables, and switch to using uv for linting and testing.
• .readthedocs.yaml: Modified the ReadTheDocs configuration to use asdf for managing dependencies and uv for building documentation.
• pyproject.toml: Added a new build system configuration using hatchling and defined project metadata, dependencies, and optional dependencies for docs, linting, and tests.
• requirements-docs.txt: Removed as dependencies are now managed in pyproject.toml.
• setup.py: Removed in favor of using pyproject.toml for build configuration.

Copilot reviewed 6 out of 10 changed files in this pull request and generated no comments.

Files not reviewed (4)

• requirements-docs.txt: Language not supported
• setup.py: Evaluated as low risk
• openvariant/variant/where.py: Evaluated as low risk
• pyproject.toml: Evaluated as low risk

Comments suppressed due to low confidence (1)

openvariant/variant/variant.py:97

• The change from AnnotationTypesProcess[ann_type].value to instance might introduce a bug if instance is not correctly defined or does not perform the same operation as AnnotationTypesProcess[ann_type].value.

header_schema.update({field: instance(ann, original_header, file_path, header_schema)})