Fix pkg_win* ci job artifact path.

The gitlab-runner starts to ignore CI_COMMIT_TAG batch variable. The path exists but I got message like this one for pkg_win_release:
WARNING: build/faust-^-amd64.exe: no matching files. Ensure that the artifact path is relative to the working directory (E:\gitlab-runner\builds\p4uM5e_P\0\faustgrp\faust)