Add option to disable modified date

This plugin is quite useful, but we have found when you are doing bulk edits for images missing alt text that it updates the modified date of the post. While this makes sense, it’s generally not great since this changes the update date in meta information, updates sitemaps, and tells Google the post has been updated, when nothing outside of image alt tags have. Please include a way to disable updating the modified date when making these changes. We don’t need Google thinking we have updated all of our post in one day.