sysutils/nerdctl: Upgrade to 1.7.6

ChangeLog: https://github.com/containerd/nerdctl/releases/tag/v1.7.6

Accumulated changes since 1.7.3:

• rootless: fix nerdctl rm failure with AppArmor on Ubuntu >= 23.10
• nerdctl-full: update containerd (1.7.16)
• nerdctl-full: update containerd (1.7.14), slirp4netns (1.2.3), CNI plugins (1.4.1), RootlessKit (2.0.2), Kubo (0.27.0), imgcrypt (1.1.10)
• rootless: Fix incompatibility with firewalld (Not Authorized(uid): org.fedoraproject.FirewallD1.config)
• nerdctl-full: Update RootlessKit (2.0.1)

PR: 279569
Reported by: laurent.chardon@gmail.com dmaintainer)