Add missing license header #3442

Job	Run time
check-lockfile	7s
lint-newsfile	36s
lint-crlf	6s
changes	3s
lint	25s
check-schema-delta	44s
check-sampleconfig	1m 5s
Typechecking	1m 32s
lint-pydantic	40s
lint-clippy	0s
lint-clippy-nightly	0s
lint-rustfmt	0s
lint-readme	0s
linting-done	2s
calculate-test-jobs	5s
portdb (3.8, 11)	3m 45s
complement (monolith, SQLite)	13m 10s
portdb (3.11, 15)	3m 7s
trial-olddeps	8m 20s
complement (monolith, Postgres)	13m 0s
complement (workers, Postgres)	21m 12s
cargo-test	0s
cargo-bench	0s
trial-pypy	0s
trial (3.8, sqlite, all)	6m 1s
sytest (focal)	8m 57s
trial (3.8, postgres, 11, all)	13m 51s
sytest (focal, postgres)	11m 32s
trial (3.8, sqlite)	5m 15s
sytest (focal, multi-postgres, workers)	13m 47s
sytest (focal, multi-postgres, workers, asyncio)	19m 3s
export-data	2m 10s
tests-done	3s
	2h 28m 38s

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