version 1.52.0 release

Compatible with NetworkManager 1.52.2, 1.54.3 or 1.56.0 and later.

Summary of changes since NetworkManager-l2tp 1.20.22 :

• Verify file permissions for private connections to prevent unprivileged user from using other user's certs (CVE-2025-9615).
  Fixes CVE-2025-9615 in combination with NetworkManager 1.52.2, 1.54.3 or 1.56.0 and later. See:
  • https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/2324
• Fixes Warning g_dbus_method_invocation_take_error: assertion 'error != NULL' failed for some strongswan failed IPsec connections.
• Merge translations from NetworkManager-fortisslvpn, NetworkManager-libreswan and NetworkManager-openvpn