update to https for tinify.php url

[girng]

getting

index.js:46458 Mixed Content: The page at 'https://free-tex-packer.com/app/' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://free-tex-packer.com/server/tinify.php'. This request has been blocked; the content must be served over HTTPS.

Looks like we need to add s to http://free-tex-packer.com/server/tinify.php

btw, tool is amazing. you are a great dev