update module: vcf2zarr/convert

[camlloyd]

PR checklist

Closes #9268 by adding index file to tests

• [x] This comment contains a description of changes (with reason).
• [ ] If you've fixed a bug or added code that should be tested, add tests!
• [ ] If you've added a new tool - have you followed the module conventions in the contribution docs
• [ ] If necessary, include test data in your PR.
• [ ] Remove all TODO statements.
• [ ] Emit the versions.yml file.
• [ ] Follow the naming conventions.
• [ ] Follow the parameters requirements.
• [ ] Follow the input/output options guidelines.
• [ ] Add a resource label
• [ ] Use BioConda and BioContainers if possible to fulfil software requirements.
• Ensure that the test works with either Docker / Singularity. Conda CI tests can be quite flaky:
  • For modules:
    • [x] nf-core modules test <MODULE> --profile docker
    • [ ] nf-core modules test <MODULE> --profile singularity
    • [ ] nf-core modules test <MODULE> --profile conda
  • For subworkflows:
    • [ ] nf-core subworkflows test <SUBWORKFLOW> --profile docker
    • [ ] nf-core subworkflows test <SUBWORKFLOW> --profile singularity
    • [ ] nf-core subworkflows test <SUBWORKFLOW> --profile conda

[SPPearce]

Um, the module doesn't take the index?

[SPPearce]

@camlloyd , do you need to update the module to take the index too?