Julia tests are failing

[manics]

Bug description

These Julia tests are failing:

• tests/julia/project-1.0.2-binder-dir
• tests/julia/require
• tests/julia/require-1-requirements-file

Expected behaviour

Tests should pass

Actual behaviour

Example:

2024-05-26T11:02:44.4780279Z   Building Conda ──→ `/srv/julia/pkg/packages/Conda/sNGum/deps/build.log`
2024-05-26T11:02:44.4780572Z   Building ZMQ ────→ `/srv/julia/pkg/packages/ZMQ/ItfqT/deps/build.log`
2024-05-26T11:02:44.4780732Z �[91m┌ Error: Error building `ZMQ`: 
2024-05-26T11:02:44.4781051Z │ ┌ Warning: platform_key() is deprecated, use platform_key_abi() from now on
2024-05-26T11:02:44.4781170Z │ │   caller = ip:0x0
2024-05-26T11:02:44.4781283Z │ └ @ Core :-1
2024-05-26T11:02:44.4782071Z │ ┌ Warning: Could not extract the platform key of https://github.com/JuliaInterop/ZMQBuilder/releases/download/v4.2.5+6/ZMQ.x86_64-linux-gnu.tar.gz; continuing...
2024-05-26T11:02:44.4782442Z │ └ @ BinaryProvider /srv/julia/pkg/packages/BinaryProvider/U2dKK/src/Prefix.jl:185
2024-05-26T11:02:44.4783477Z │ [ Info: Downloading https://github.com/JuliaInterop/ZMQBuilder/releases/download/v4.2.5+6/ZMQ.x86_64-linux-gnu.tar.gz to /srv/julia/pkg/packages/ZMQ/ItfqT/deps/usr/downloads/ZMQ.x86_64-linux-gnu.tar.gz...
2024-05-26T11:02:44.4784574Z │ ERROR: LoadError: Could not download https://github.com/JuliaInterop/ZMQBuilder/releases/download/v4.2.5+6/ZMQ.x86_64-linux-gnu.tar.gz to /srv/julia/pkg/packages/ZMQ/ItfqT/deps/usr/downloads/ZMQ.x86_64-linux-gnu.tar.gz:

https://github.com/JuliaInterop/ZMQBuilder/releases/download/v4.2.5+6/ZMQ.x86_64-linux-gnu.tar.gz does not exist

How to reproduce

https://github.com/jupyterhub/repo2docker/actions/runs/9242619853/job/25425671430

[minrk]

Looks like the very old builds rely on a repo that's been deleted: JuliaInterop/ZMQ.jl#228 and we can't really support Julia 0.6 anymore.

[minrk]

actually, it might be that we have to drop support for Julia REQUIRE altogether

[minrk]

#1350 removes REQUIRE and support for Julia < 1.3, which is the oldest version that can build ZMQ.jl now.