Doctool: Remove version attribute from XML header #3302

Job	Run time
📊 Static / Static Checks (clang-format, black format, file format, documentation checks)	2m 54s
🌐 JavaScript / Template (target=release, tools=no)	12m 57s
🤖 Android / Template (target=release, tools=no)	15m 21s
🍏 iOS / Template (target=release, tools=no)	4m 55s
🐧 Linux / Editor w/ Mono (target=release_debug, tools=yes)	28m 23s
🐧 Linux / Editor and sanitizers (target=debug, tools=yes, use_asan=yes, use_ubsan=yes, linker=gold)	34m 44s
🍎 macOS / Editor (target=release_debug, tools=yes)	9m 14s
🐧 Linux / Template w/ Mono (target=release, tools=no)	14m 1s
☁ Server / Linux Headless w/ Mono (target=release_debug, tools=yes)	19m 30s
🏁 Windows / Editor (target=release_debug, tools=yes)	21m 2s
🐧 Linux / Minimal template (target=release, tools=no, everything disabled)	9m 4s
🍎 macOS / Template (target=release, tools=no)	4m 19s
☁ Server / Linux Server w/ Mono (target=release, tools=no)	12m 5s
🏁 Windows / Template (target=release, tools=no)	17m 13s
	3h 25m 42s

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