Various problems executing tests

[captaincoordinates]

While configuring a local development environment I encountered a number of problems executing tests. I have fixes for each of these problems, PR here.

1. poetry install fails on macOS (Apple Silicon) and Debian (AMD) with an error message citing "AttributeError: cython_sources". Fixed with poetry update --lock.
2. poetry run python admin.py build --tests fails due to httpx dependency cgi not existing. fixed with poetry update --lock.
3. development.md documentation does not mention that poetry run python admin.py build --tests must be executed prior to ./run-tests.sh, as the test process assumes that test files are included in the build directory. Fixed with documentation update.
4. ./run-tests.sh returns a 0 exit code when tests fail, potentially misleading developers expecting a non-0 exit code. Fixed by returning non-0 if present.
5. Race condition observed in test_stac_api_client_functions.py due to the Flask mock API server starting in a separate process without a mechanism to wait for the server before executing tests in the main process. Test failures were unpredictable and somewhat random. Fixed with a function that polls the mock API server before returning or raising an exception.