Reinstate environment variables on Windows CI #46

Job	Run time
Conan (windows-2019, Debug, shared=True)	3m 10s
Conan (windows-2019, Debug, shared=False)	4m 12s
Conan (Debug, 9, shared=True)	27s
Conan (windows-2019, Release, shared=True)	2m 53s
Conan (Debug, 9, shared=False)	41s
Conan (windows-2019, Release, shared=False)	4m 0s
Conan (Release, 9, shared=True)	32s
Conan (windows-2022, Debug, shared=True)	2m 27s
Conan (Release, 9, shared=False)	29s
Conan (windows-2022, Debug, shared=False)	2m 27s
Conan (windows-2022, Release, shared=True)	2m 40s
Conan (windows-2022, Release, shared=False)	3m 58s
	27m 56s

Provide feedback