validate if url is image

[quintenvandamme]

Pull request template

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• PRs that don't have the template filled out will be ignored

Description

• Please include a summary of the change and which issue is fixed
• Please also include relevant motivation and context (Why is this change required? What problem does it solve?)
• List any dependencies that are required for this change
• If it fixes an open issue, plase link to the issue here

Fixes #(issue)

Screenshots (if appropriate):

Type of change

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• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Checklist:

• [x] My code follows the guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [ ] All current GitHub actions pass
• [ ] Any dependent changes have been merged and published in downstream modules
• [ ] I have checked my code and corrected any misspellings
• [ ] I have read the CONTRIBUTING document