Bump to TypeScript 5.6 /w strictPropertyInit #1541

Job	Run time
pylint (macos)	47s
lint (npm run lint:eslint, macos)	1m 32s
pylint (ubuntu)	16s
lint (npm run lint:eslint, ubuntu)	1m 24s
todo-check	2s
pylint (windows)	32s
lint (npm run lint:eslint, windows)	5m 23s
lint (npm run lint:yaml, macos)	1m 44s
validate-collection-files (macos)	14s
lint (npm run lint:yaml, ubuntu)	50s
validate-collection-files (ubuntu)	20s
lint (npm run lint:yaml, windows)	5m 28s
validate-collection-files (windows)	54s
lint (npm run lint:md, macos)	1m 12s
lint (npm run lint:md, ubuntu)	49s
lint (npm run lint:md, windows)	5m 36s
lint (npm run lint:md:consistency, macos)	55s
lint (npm run lint:md:consistency, ubuntu)	49s
lint (npm run lint:md:consistency, windows)	4m 25s
lint (npm run lint:md:relative-urls, macos)	57s
lint (npm run lint:md:relative-urls, ubuntu)	57s
lint (npm run lint:md:relative-urls, windows)	4m 14s
lint (npm run lint:md:external-urls, macos)	2m 42s
lint (npm run lint:md:external-urls, ubuntu)	2m 10s
lint (npm run lint:md:external-urls, windows)	4m 22s
	48m 34s

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