.build/push-artifacts: also push tags

The tags for the loxigen-artfacts repository were generated locally
but not sent to github.
diff --git a/.build/push-artifacts.sh b/.build/push-artifacts.sh
index fd607eb..8c7b60b 100755
--- a/.build/push-artifacts.sh
+++ b/.build/push-artifacts.sh
@@ -54,6 +54,7 @@
     ) | git commit --file=-
 
     git tag -a -f "loxi/${loxi_head}" -m "Tag Loxigen Revision ${loxi_head}"
+    git push --tags
     git push
 )