update: add SPDX license identifier #1900

Job	Run time
fetch-version / fetch-version	27s
build-dev / build-and-test	10m 56s
build-dev-minimal / build-and-test	4m 29s
build-dev-packages / build-musl-package	1h 1m 53s
build-dev-packages / build-modern-bpf-skeleton	3m 15s
build-dev-packages / build-wasm-package	11m 6s
build-dev-packages / build-packages	36m 58s
check-engine-version	3s
check-engine-checksum	6s
test-dev-packages / test-packages	3m 14s
test-dev-packages (static) / test-packages	1m 57s
	2h 14m 24s

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