You are serving your site from a subdirectory named blog:
baseURL = "https://pedrojunqueira.github.io/blog"
So the path to the image will be:
/blog/img/sql.png
Files within the static directory are copied to the root of the public directory when you build your site, so you never include static in the path. See: https://gohugo.io/content-management/static-files/