Issues with debian repository
I have some issues to access the Debian repository https://bird.network.cz/debian. I get a certificate verification error. The used certificate is signed by "Let's Encrypt Authority X3" which is not part of the ca-certifcate package on a Debian or Ubuntu system. I think you should ship the certificate as intermediate certificate. Let's encrypt lists this certificate as intermediate certificate, not as a root certificate: https://letsencrypt.org/certificates/