Remove whitespace in `operator"" _a` #4682

Job	Run time
mingw (mingw64)	6m 15s
mingw (ucrt64)	6m 19s
build (windows-2019, Win32, v142, 17, Debug)	2m 23s
build (windows-2019, Win32, v142, 17, Release)	3m 24s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 46s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	3m 46s
build (windows-2019, x64, v140, 14, Debug)	1m 45s
build (windows-2019, x64, v140, 14, Release)	2m 55s
build (windows-2019, x64, v141, 17, Debug)	2m 28s
build (windows-2019, x64, v141, 17, Release)	3m 29s
build (windows-2019, x64, v142, 17, Debug)	1m 50s
build (windows-2019, x64, v142, 17, Release)	3m 43s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	3m 5s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	3m 49s
build (windows-2019, x64, v142, 20, Debug)	2m 56s
build (windows-2019, x64, v142, 20, Release)	4m 55s
build (windows-2022, x64, v143, Debug, 20)	3m 23s
	58m 11s

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