Add 'infer' version option when downloading from iiif

[rwood-97]

Summary

Allowing infer for downloading iiif maps as I've update it in piffle

Checklist before assigning a reviewer (update as needed)

• Self-review code
• Ensure submission passes current tests
• Add tests
• Update relevant docs
• Update changelog

Reviewer checklist

Please add anything you want reviewers to specifically focus/comment on.

• Everything looks ok?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
unittests	79.30% <100.00%> (ø)

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Files with missing lines	Coverage Δ
mapreader/download/iiif_downloader.py	78.26% <100.00%> (ø)

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