Remove double-slash from IIIF canvas Ids.

[alxp]

GitHub Issue: [BUG] islandora_iiif generating incorrect canvas IDs

What does this Pull Request do?

Fixes a bug where canvas Ids in IIIF manifests would have double slashes in the URL.

What's new?

• Does this change add any new dependencies? No
• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? No
• Could this change impact execution of existing code? Yes, if code was relying on the existing canvas URLs.

How should this be tested?

A description of what steps someone could take to:

• Reproduce the problem you are fixing (if applicable)

See steps in issue.

Documentation Status

• Does this change existing behaviour that's currently documented? No
• Does this change require new pages or sections of documentation? No
• Who does this need to be documented for? N/A
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag (@ mention) interested parties or, if unsure, @Islandora/committers @bibliophileaxe

@adam-vessey

[wgilling]

The code has been reviewed and the id looks good