Add tests for Julia metadata handling - #1143

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good

Thanks for the review. I tightened the Julia metadata tests so every ecosystem.julia.request_json call now goes through a strict URL-to-payload mock. If the code tries any unexpected URL, the test raises an assertion instead of silently returning a fallback value. The tests also assert the exact mocked request sequence for the JuliaHub, registry, download stats, and GitHub tree probes.

Verified locally:

• python -m unittest tests.models.test_julia -v
• python -m black --check tests/models/test_julia.py
• python -m pylint -rn tests/models/test_julia.py

Thanks, I pushed a follow-up in 2fb327a to address both points.

Changes:

• replaced the real-looking Flux fixture with a synthetic BananaCompiler Julia package so the tests do not look tied to a specific real package
• moved the tests that were setting private Julia metadata state directly onto mocked request_json plus the public update_json() path
• kept the strict ordered URL mock, so any unexpected JuliaPackages, JuliaHub, registry, stats, or GitHub tree request fails the test

Verified locally:

• python -m unittest tests.models.test_julia -v
• python -m unittest discover -s tests/models -v
• python -m coverage run --source=ecosystem.julia -m unittest tests.models.test_julia && python -m coverage report -m -> ecosystem/julia.py at 91%
• python -m black --check tests/models/test_julia.py
• python -m pylint -rn tests/models/test_julia.py
• git diff --check