CMakeLists.txt: Make QtSparkle optional on Windows builds #3706

Job	Run time
Build macOS Private	0s
Build macOS Public (macos-13, release)	28m 22s
Build Fedora (39)	27m 12s
Build macOS Public (macos-14, release)	15m 32s
Build Debian (bookworm)	21m 29s
Build Fedora (40)	27m 50s
Build Debian (trixie)	20m 59s
Build Mageia (9)	25m 18s
Build Fedora (41)	25m 24s
Build OpenMandriva	0s
Build openSUSE (tumbleweed)	19m 39s
Build Ubuntu (noble)	23m 55s
Build openSUSE (leap:15.6)	20m 49s
Build Windows MinGW (i686, debug)	26m 17s
Build Windows MSVC (x86, release)	30m 26s
Build Ubuntu (oracular)	21m 48s
Build Windows MinGW (i686, release)	16m 23s
Build Windows MSVC (x86_64, release)	33m 38s
Build Windows MinGW (x86_64, debug)	26m 1s
Upload Ubuntu PPA	0s
Build Windows MinGW (x86_64, release)	16m 47s
Upload	0s
Attach to release	0s
	7h 7m 49s

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