This does a full upload of the sandbox project to the test.pypi.org
service.
It uses the inline token with the caveats noted in the comment. Since
you can't upload the same version twice, always running this in the
check job will mean it will work the first time, but then fail (unless
something has been committed to the sandbox to update the version
number). As noted, the idea is that we develop the change and then do
one run that does a full test, and reviewers can check that before
committing. There's no real way to use a secret here because we
actually want this to run at check time, not in any post pipeline
where it would already be in production. We don't want to do
something like require committing something to sandbox every time you
run this in the check queue, etc. Given how much this is actually
updated (most of it hasn't been touched since 2019) I think this is a
reasonable compromise.
Change-Id: Ida4ad07c82a6301107c938565656988aba3bf250
673a499e7b