ci: build the pure-Python (py3-none-any) wheel as a pinned-artifact f…

…or wasm consumers

VPYTHON_PURE_PYTHON=1 wheel built on every push to master/pyodide-packaging,
verified pure + importable, sha256-summed, uploaded as an actions artifact,
and attached to GitHub releases. Downstream (trinket) pins by URL + sha256.
Also gitignore local virtualenvs.

Release version 7.6.5

Merge pull request #274 from jcoady/jupyterlab4

updated some no_notebook demo programs

Merge pull request #273 from jcoady/jupyterlab4

Added some demos from webvpython

Merge pull request #267 from vpython/bounding_box

fix bound_box

Merge pull request #264 from jcoady/jupyterlab4

add jupyterlab-vpython to install-requires list

Merge pull request #260 from vpython/dotcolor

Fix dot_color

Merge pull request #259 from mwcraig/update-contributors

Update contributors

Merge pull request #258 from mwcraig/update-build-matrix-pt312

Update build matrix for Python 3.12

Merge pull request #212 from mwcraig/add-cython-ubild-dep

Add Cython to build dependencies