Remove `fmt/core.h` from docs #8129

Job	Run time
mingw (ucrt64)	4m 42s
mingw (mingw64)	4m 15s
build (windows-2019, Win32, v142, 17, Debug)	1m 43s
build (windows-2019, x64, v141, 14, Release)	2m 6s
build (windows-2019, x64, v141, 17, Release)	2m 45s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 21s
build (windows-2019, x64, v141, 14, Debug)	1m 42s
build (windows-2019, x64, v142, 17, Release)	2m 32s
build (windows-2019, x64, v142, 17, Debug)	1m 27s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 7s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 36s
build (windows-2019, Win32, v142, 17, Release)	2m 0s
build (windows-2022, x64, v143, Debug, 20)	2m 36s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 17s
build (windows-2019, x64, v142, 20, Debug)	1m 32s
build (windows-2019, x64, v141, 17, Debug)	1m 28s
build (windows-2019, x64, v142, 20, Release)	2m 39s
	38m 48s

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