ISBAT See Gallery image ALT text in lighbox instead of "Placeholder"

### Describe the bug:
When opening gallery image in a lightbox it shows ALT text as "Placeholder", instead of the ALT value set for that image

### To reproduce:
1. Set Alternative Text (ALT) for couple of images
2. Add Gallery block to page (with above images)
3. Enable Lightbox option for Gallery
4. Open any gallery image and inspect it, you will see ALT value showing "Placeholder"

### Expected behavior:
Alternative Text set for image should show instead of "Placeholder" text.

### Screenshots:

### Isolating the problem:
- [x] This bug happens with no other plugins activated
- [x] This bug happens with a default WordPress theme active
- [x] This bug happens **without** the Gutenberg plugin active
- [x] I can reproduce this bug consistently using the steps above

### WordPress version:
6.7.2

### CoBlocks version:
3.1.14

### Gutenberg version:
N/A