Re: intent to ship: sha2 windows signing

Per https://jira.mozilla.com/browse/RELENG-431, backwards compatibility with win7 sp0 may not be a big issue, though I'm happy to delay rollout if there are any additional concerns. I've linked sha2-signed artifacts in that ticket; we may want to have a QA pass before we decide to roll out. On Wed

intent to ship: sha2 windows signing

Per https://bugzilla.mozilla.org/show_bug.cgi?id=1697185#c4 and https://jira.mozilla.com/browse/RELENG-429 . We haven't made a product-level decision here, but a) it looks like timestamp.digicert.com may have silently EOLed sha1 timestamps since Microsoft has EOLed sha1 signing years ago, and b) i