Add structure hook for Union[str, List[InlayHintLabelPart]]

[alcarney]

Fixes #218

[karthiknadig]

@alcarney It looks like how pygls used to run tests has changed. Would it be possible for you to update the github workflow so that we can run pygls tests as smoke tests?

[alcarney]

It is not immediately obvious to me why the test suite would hang before running any tests - especially when they seem to run fine over on the pygls repo....

But I will have a look and see if I can reproduce it locally

[karthiknadig]

@alcarney I was running pytest directly, but it looks like we should probably use tox to run pygls tests.

[alcarney]

@karthiknadig I reproduced it locally - test suite hangs on the second test.
I seem to remember having issues with that test when I wrote it originally - hopefully I can remember what the issue was!

================================================= test session starts =================================================
platform linux -- Python 3.11.3, pytest-7.3.2, pluggy-1.0.0
rootdir: /var/home/alex/Projects/lsprotocol/smoke_tests
configfile: pyproject.toml
plugins: typeguard-4.0.0, asyncio-0.21.0
asyncio: mode=Mode.AUTO
collected 213 items                                                                                                   

smoke_tests/tests/test_client.py::test_client_detect_server_exit 
--------------------------------------------------- live log setup ----------------------------------------------------
DEBUG    asyncio:selector_events.py:54 Using selector: EpollSelector
DEBUG    asyncio:selector_events.py:54 Using selector: EpollSelector
---------------------------------------------------- live log call ----------------------------------------------------
DEBUG    pygls.client:client.py:110 Starting server process: /var/home/alex/Projects/lsprotocol/.ci/bin/python -c print('Hello, World!')
DEBUG    pygls.client:client.py:134 Server process 105533 exited with return code: 0
PASSED                                                                                                          [  0%]
-------------------------------------------------- live log teardown --------------------------------------------------
DEBUG    asyncio:selector_events.py:54 Using selector: EpollSelector

smoke_tests/tests/test_client.py::test_client_detect_invalid_json 
--------------------------------------------------- live log setup ----------------------------------------------------
DEBUG    asyncio:selector_events.py:54 Using selector: EpollSelector
---------------------------------------------------- live log call ----------------------------------------------------
DEBUG    pygls.client:client.py:110 Starting server process: /var/home/alex/Projects/lsprotocol/.ci/bin/python /var/home/alex/Projects/lsprotocol/smoke_tests/tests/servers/invalid_json.py
DEBUG    pygls.protocol:protocol.py:583 Sending request with id "e7f074c7-fca1-485e-881a-9b94dde57a17": method/name {}
INFO     pygls.protocol:protocol.py:462 Sending data: {"id": "e7f074c7-fca1-485e-881a-9b94dde57a17", "method": "method/name", "jsonrpc": "2.0", "params": {}}
DEBUG    pygls.client:client.py:134 Server process 105539 exited with return code: 1