Update cfitsio to 4.0.0
This fixes the issue of cfitsio installing an empty uniunistd.h . 4.0.0 is not listed in https://abi-laboratory.pro/index.php?view=timeline&l=cfitsio but previous releases already required a rebuild.
When testing with kstars I only reached wcslib which failed due to the now no longer existing uniunistd.h .