Tests

Add note about MSC3886 being closed #1132

Job	Run time
changes	3s
check-lockfile	6s
lint-crlf	8s
lint-newsfile	32s
lint	45s
Typechecking	1m 22s
check-sampleconfig	40s
check-schema-delta	38s
lint-pydantic	39s
lint-clippy	0s
lint-clippy-nightly	0s
lint-rustfmt	0s
linting-done	1s
calculate-test-jobs	6s
portdb (3.8, 11)	2m 50s
complement (monolith, SQLite)	12m 44s
trial-olddeps	6m 27s
portdb (3.11, 15)	2m 45s
complement (monolith, Postgres)	13m 49s
cargo-bench	0s
cargo-test	0s
trial-pypy	0s
complement (workers, Postgres)	19m 59s
sytest (focal)	8m 36s
trial (3.8, sqlite, all)	3m 59s
sytest (focal, postgres)	10m 41s
trial (3.8, postgres, 11, all)	10m 5s
sytest (focal, multi-postgres, workers)	13m 24s
trial (3.8, sqlite)	3m 42s
sytest (focal, multi-postgres, workers, asyncio)	19m 43s
export-data	2m 6s
tests-done	3s
	2h 15m 53s

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