alabaster: upgraded package to upstream

Upgraded dev-python/alabaster to version 0.7.12 on amd64, arm

It's needed by sphinx.

BUG=chromium:999876
TEST=update_chroot

Change-Id: I5b4a605298b8ff27938aedb8401419c8588d6080
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2219760
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Yilin Yang (kerker) <kerker@chromium.org>
Tested-by: Yilin Yang (kerker) <kerker@chromium.org>
4 files changed