fix(#3554): correct `module_to_os_path` to return directory paths #3882

Job	Run time
mypy	1m 14s
pyright	59s
slotscheck	29s
Test server integration (uvicorn<0.27.0)	54s
Test Minimal Application with Base Dependencies	31s
Test Minimal Pydantic 1 application	45s
Test server integration (uvicorn>=0.27.0)	54s
validate	13s
test-platform-compat	0s
test (3.10) / test	2m 2s
test (3.11) / test	1m 57s
test (3.12) / test	3m 38s
test (3.9) / test	2m 6s
test (3.8) / test	2m 59s
build-docs	2m 47s
upload-test-coverage	19s
codeql	2m 37s
sonar	0s
	24m 24s

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