No orjson for PyPy

[evnchn]

Motivation

As mentioned in zauberzeug/rosys#301 (comment), NiceGUI does not work under PyPy normally. I discovered the reason (at least one of it) being orjson, as "orjson does not and will not support PyPy" (https://github.com/ijl/orjson/blob/aa8c946cfbe2aba29016bc9c9ddc8713cb00173b/README.md?plain=1#L35)

It would be a pity if we can't use NiceGUI under PyPy since its garbage collector does not "stop the world" unlike CPython's, an awesome use case for the robots which RoSys may empower

Implementation

Add platform_python_implementation != 'PyPy' to the markers of orjson marking it out of 32-bit systems, such that if it is PyPy orjson will not be installed.

This is inspired from https://github.com/pyca/cryptography/blob/cac6426aafd989e4d8d9c4f6b920a332a5280bba/pyproject.toml#L8

Progress

• I chose a meaningful title that completes the sentence: "If applied, this PR will..."
• The implementation is complete.
• Pytests have been are not necessary.
  • Original Pytests already handle missing orjson. Check

    nicegui/tests/test_json.py

    Lines 13 to 20 in a6354dc

    	try:
    	# try to import module, only run test if succeeded
    	import orjson # noqa: F401
    	except ImportError:
    	pass
    	@pytest.mark.skipif('orjson' not in sys.modules, reason='requires the orjson library.')

• Documentation is not necessary.
  • But do make it very clear that this is BETA or even ALPHA level support...

[evnchn]

It works. I tried it in the devcontainer.

• sudo apt install pypy3 pypy3-dev pypy3-venv
• pypy3 -m venv venv_pypy then source venv_pypy/bin/activate
• pip install git+https://github.com/MagicStack/httptools@e265ae0 (Why: Check pip install failing for pypy3.11 MagicStack/httptools#122 (comment))
• pip install -e .
• pip install isort to run the documentation website, by the way.

[evnchn]

Feel like we should YOLO and merge this.

Originally:

• Works for CPython.
• Does NOT work for PyPy whatsover.

Now:

• Still works for CPython, platform_python_implementation != 'PyPy' is true after all.
• If it doesn't work for PyPy, we're not regressing; But if it does then great!

Tests pass, by the way (https://github.com/evnchn/nicegui/actions/runs/17919770924). Please ignore 3.9-3.12 results on my branch since their cache's messed up.

[evnchn]

#5163 is better.

[evnchn]

I'm not up to resolving merge conflict for a partial PR...