Add instructions for downloading the alternate MSYS2 unpacker #3134

Job	Run time
Build package	4s
Static Analysis	10s
Build package	11s
Call ci unit tests workflow / Run tests (3.11)	2m 52s
Call ci unit tests workflow / Run tests (3.10)	3m 6s
Call ci unit tests workflow / Run tests (3.12)	3m 9s
	9m 32s

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