Use Python Stable ABI in Swig build

[DavidMStraub]

Closes #18

Also updated the version.

Still need to update the workflow

[Copilot]

Pull Request Overview

This PR implements Python Stable ABI (abi3) support for the SWIG-generated rundec Python wrapper. The main changes include:

• Adding Stable ABI macros to setup.py and rundec.i to enable building abi3-compatible wheels
• Updating from SWIG 4.2.0 to 4.3.0 with corresponding code generation changes
• Updating the minimum supported Python version from 2.7/3.5+ to 3.10+
• Modernizing the GitHub Actions workflow to build abi3 wheels

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
setup.py	Added py_limited_api=True and Py_LIMITED_API macro definition; updated version to 0.7 and author email
rundec.i	Added %begin block to define Py_LIMITED_API before SWIG includes
_rundec.cc	SWIG-generated file updated from 4.2.0 to 4.3.0 with Stable ABI compatibility changes
rundec.py	SWIG version comment updated from 4.2.0 to 4.3.0
README.md	Updated Python version requirement from 2.7/3.5+ to 3.10+
.github/workflows/wheels.yml	Added sdist build job, restricted wheel builds to cp310-* for abi3, updated OS versions, added release trigger
.github/workflows/test.yml	Updated test matrix from Python 3.7-3.10 to 3.10-3.14

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