running tests should not modify committed files

[yarikoptic]

having ran tests is changing a committed file

❯ git co -
Switched to branch 'main'
Your branch is up to date with 'origin/main'.
❯ python -m pytest -sv .
=============================================================================== test session starts ================================================================================
platform linux -- Python 3.12.4, pytest-8.3.1, pluggy-1.5.0 -- /home/yoh/proj/dandi/linkml-aind-model/venv/3.12/bin/python
cachedir: .pytest_cache
rootdir: /home/yoh/proj/dandi/linkml-aind-model
collected 2 items                                                                                                                                                                  

test_cli.py::test_smoke_cli PASSED
test_converters.py::test_smoke Success!
PASSED

================================================================================ 2 passed in 1.06s =================================================================================
changes on filesystem:                                                                                                                                                              
 generated_linkml_models/aind.yml | 3512 --------------------------------------

which it shouldn't do (test should operate on a copy in a temp repo)