chore: adjust the regex for previewing images so that it only attempts to render if the image has a bracket immediately preceding the parentheses

[mayraamaral]

Problem

When the alt of an image has parentheses inside of it and previewImagesInEditor is true, the editor tries to render the image by making a GET with everything thats after the opening parentheses, e.g.:

![My alt (that has a parentheses)](my image url)

it tries to do a GET using the base url of the site + that has a parentheses)](my image url) and it results in a 404 error
Example:
http://localhost:8000/that%20has%20a%20parentheses)](my%20image%20url

Solution

in this PR i just fixed the regex that was used to match the src of an image 😄

[mayraamaral]

FYI @Ionaru,
I updated the actions to v4 and accidentally pushed the commit here, but I fixed it and opened this new PR: #609.

Please let me know if there’s anything else I can help with! 😄