HtmlFilter: use <s> instead of <strike> #713

Job	Run time
Prepare	1s
Build (ubuntu-22.04, 6, own-quotient)	3m 29s
Build (ubuntu-22.04, 6, static)	3m 17s
Build (ubuntu-22.04, 6, dynamic)	2m 44s
Build (ubuntu-22.04, 6, GCC, own-quotient)	4m 20s
Build (ubuntu-22.04, 6, GCC, static)	4m 8s
Build (ubuntu-22.04, 6, GCC, dynamic)	3m 53s
Build (macos-latest, 6, own-quotient)	1h 4m 7s
Build (macos-latest, 6, static)	1h 1m 42s
Build (windows-latest, 6, own-quotient)	13m 37s
Build (windows-latest, 6, static)	12m 46s
Build (ubuntu-22.04, 5, own-quotient, appstream)	2m 56s
Build (ubuntu-22.04, 5, static)	2m 28s
Build (ubuntu-22.04, 5, dynamic, codeql)	4m 28s
Publish (macOS)	40s
Publish (Linux)	33s
Publish (Windows)	2m 51s
	3h 8m 0s

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