[CMake] Correct pugixml-1.9 url/hash.
[CMake] Correct pugixml-1.9 url/hash.

I really messed up here.
https://github.com/zeux/pugixml/issues/237

LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed