This package is deprecated because CSP support has been added to the nette/http package in version 2.4.4...

Nette/http package does have very similar syntax and additionally it support nonces. Here is the future syntax:

http:
    csp:
        default-src: "'self' https://example.com"
        upgrade-insecure-requests:
        script-src: 'nonce'
        style-src:
            - self
            - https://example.com

Yeah that's right - you don't have to register special extension, because it's already in Nette Framework. Please read more about nonce support in Nette Framework forum.