Gallery image is distorted in opening animation

When using images in the gallery element, the opening animation distorts the image when it doesn't exactly fit the aspect ratio of the gallery thumbnails.

## Steps to Reproduce

1. Use gallery element
2. Include images with different aspect ratios
3. Choose a layout and make the images clickable

### Expected behavior

The images open in a smooth transition.

### Actual behavior

The images are distorted during the animation.

### Screenshots

https://user-images.githubusercontent.com/85571517/214696236-f7638678-cf35-425a-8d69-493c22311a82.mov

## Versions

Typo3 11.5.22
Bootstrap Package 13.0.1
PHP 7.4.33

## References

The animation was added in PR https://github.com/benjaminkott/bootstrap_package/pull/941 .