Add missing include in spectran source #1279

Job	Run time
build_debian_buster	2m 59s
build_macos_arm	2m 12s
build_windows	11m 40s
build_macos_intel	4m 31s
build_android	11m 52s
build_debian_bookworm	3m 36s
build_debian_sid	3m 48s
build_debian_bullseye	3m 3s
build_raspios_bullseye_armhf	9m 0s
build_ubuntu_focal	3m 27s
build_ubuntu_jammy	3m 18s
build_ubuntu_mantic	3m 11s
check_formatting	11s
check_spelling	13s
create_full_archive	9s
update_nightly_release	6s
	1h 3m 16s

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