add shfmt #77

Job	Run time
update_flake	55s
generate_matrix	55s
check_flake	18m 46s
build_images (x86_64, linux, server, proxmox)	10m 33s
build_images (x86_64, linux, server, raw-efi)	10m 20s
build_images (x86_64, linux, server, iso)	10m 55s
build_flake (cb)	57s
build_images (x86_64, linux, bri, proxmox)	16m 35s
build_flake (pyEnv)	1m 42s
build_images (x86_64, linux, bri, raw-efi)	17m 49s
build_flake (sysdo)	1m 0s
build_images (x86_64, linux, bri, iso)	32m 21s
push_update	0s
	2h 2m 48s

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