### Pull Request: Fix .webp SrcSet Creation Filter
#### Description
This PR addresses an issue with the filter for creating `.webp` srcsets
introduced in PR #2698. The original filter incorrectly searched for
extensions with a leading period (e.g., ".jpg" and ".png"). As a result,
no matches were found, preventing the srcset from being added to any
figures. This occurred because the split operation removes the period
from the file extensions.
#### Changes Made
- Updated the filter to search for file extensions without the leading
period (e.g., "jpg" and "png").
- Ensured that the resource sets are now correctly created for the
respective file extensions, allowing the `.webp` srcset to function as
intended.
#### Impact
With this change, responsive images will now correctly generate their
srcsets for the appropriate file types, improving image loading
performance and supporting better responsiveness.
#### Fixes
- Fixes#2777
Please review the changes and let me know if there are any further
adjustments needed. Thank you!
b3f1968422