[Bug]: Hard coded Content-Type in example MyAssetController class for asset protection

[elbkapitaenehh]

Expected behavior

A protected asset should be delivered with the correct Content-Type header after one included the example code for the MyAssetController class from https://pimcore.com/docs/pimcore/10.6/Development_Documentation/Assets/Restricting_Public_Asset_Access.html#page_Option-2-Checking-permissions-before-delivery

Actual behavior

The Content-Type header is hard coded as application/pdf. It should be $asset->getMimeType() in order to match the delivered asset MimeType

Steps to reproduce

1. Implement the solution documented in https://pimcore.com/docs/pimcore/10.6/Development_Documentation/Assets/Restricting_Public_Asset_Access.html#page_Option-2-Checking-permissions-before-delivery
2. Upload any non-pdf asset in the protected folder
3. Authenticate and open the public link
4. The Content-Type says 'application/pdf'