Fix broken links to neuro.polymtl.ca

[joshuacwnewton]

Checklist

GitHub

• I've given this PR a concise, self-descriptive, and meaningful title
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PR contents

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Description

Very tiny PR for a very tiny issue.

Linked issues

Fixes #3685.

[codecov]

Codecov Report

Merging #3690 (9c76460) into master (34286e2) will not change coverage.
The diff coverage is n/a.

Flag	Coverage Δ
api-tests	24.45% <ø> (ø)
cli-tests	56.85% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
spinalcordtoolbox/centerline/nurbs.py	52.71% <ø> (ø)
spinalcordtoolbox/registration/landmarks.py	79.52% <ø> (ø)

[RignonNoel]

LGTM