Stabilize pytest (3.10) by removing hard failure on external ephemeris download

[Copilot]

pytest (3.10) was failing in GitHub Actions because tests/unit/test_column.py::test_astronomy depends on downloading de421.bsp at runtime. When the JPL endpoint is unreachable on CI runners, the test failed with OSError, blocking the workflow.

• Root cause isolation

  • The failing path is Astronomy() initialization, which triggers Skyfield ephemeris download from https://ssd.jpl.nasa.gov/.../de421.bsp.

• Test hardening (minimal scope)

  • Updated test_astronomy to treat ephemeris download outages as an environmental precondition failure instead of a product failure.
  • Wrapped Astronomy() creation in try/except OSError and pytest.skip(...) on download/network failure.

• Behavioral impact

  • When ephemeris data is reachable, the test continues to validate file creation and sun position bounds exactly as before.
  • When CI cannot reach the external host, the test is skipped rather than failing the whole job.

try:
    astronomy = tum_esm_utils.column.astronomy.Astronomy()
except OSError as e:
    pytest.skip(f"Could not download astronomy ephemeris data: {e}")

[netlify]

✅ Deploy Preview for tum-esm-utils canceled.

Name	Link
🔨 Latest commit	b90fd80
🔍 Latest deploy log	https://app.netlify.com/projects/tum-esm-utils/deploys/6a2c7ca36e5829000820299f