0.22.0-release-notes.md: Document removal of external dependencies fr… #1783

Job	Run time
Run benchmarks	1m 31s
Run checks (ubuntu)	39s
Run checks (macos)	24s
Run tests (emulated riscv64)	1m 7s
Run checks (windows)	3m 10s
Run tests (ubuntu, 1.23.x)	1m 37s
Run tests (emulated s390x)	1m 8s
Run tests (macos, 1.23.x)	1m 45s
Run tests (windows, 1.23.x)	4m 24s
Check relative links in website	9s
Run tests (ubuntu, 1.22.x)	26s
Upload test coverage (linux)	18s
Upload test coverage (macos)	14s
Upload test coverage (windows)	14s
	17m 6s

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