Add pyproject, mypy, bump version

[nllong]

Add in a pyproject, but it isn't required, just supports projects using poetry.

Setup mypy config, but don't enforce, yet.

[Copilot]

Pull Request Overview

This PR adds build system configuration and development tooling support to the project while incrementing the version number. The changes include adding pyproject.toml for modern Python packaging, configuring mypy for type checking, and adding a CI build status badge to the README.

• Added pyproject.toml with build system configuration and tool settings for mypy and ruff
• Created mypy.ini configuration file for type checking
• Updated version from 2.1.2 to 2.1.3 and added CI status badge to README

Reviewed Changes

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

File	Description
pyproject.toml	New file with build system configuration and tool settings for mypy/ruff
mypy.ini	New mypy configuration file with basic type checking settings
buildingid/version.py	Version bump from 2.1.2 to 2.1.3
README.rst	Added GitHub Actions build status badge

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