- Add floppy disk image.
* use syslinux-mtools for building the image syslinux-mtools.patch

- Update to version 1.21.1+git20231006.ff0f8604:
* [libc] Use wall clock time as seed for the (non-cryptographic) RNG
* [eapol] Send EAPoL-Start packets to trigger EAP authentication
* [eap] Define a supplicant model for EAP and EAPoL
* [dhcp] Request NTP server option
* [ntp] Define NTP server setting
* [efi] Provide read-only access to EFI variables via settings mechanism
* [crypto] Add support for PKCS#8 private key format
* [efi] Add support for executing images via a shim
* [image] Generalise concept of selected image
* [tls] Handle fragmented handshake records (jsc#PED-5536)
* [params] Allow for arbitrary HTTP request headers to be specified
* [rng] Allow entropy source to be selected at runtime
* [efi] Support the initrd autodetection mechanism in newer Linux kernels
* [loong64] Add initial support for LoongArch64
* [efi] Enable NET_PROTO_LLDP by default
* [dhcp] Ignore DHCPNAK unless originating from the selected DHCP server
* [xen] Update to current Xen headers
* [efi] Allow autoexec script to be located alongside iPXE binary
* [efi] Accept a command line passed to an iPXE image via LoadOptions
* [efi] Update to current EDK2 headers
* [golan] Add new PCI ID for NVIDIA BlueField-3 network device
* [arm] Support building as a Linux userspace binary for AArch64