Release Procedure

Verify that the new version's snowflake--X.Y.sql exists.
Make sure that the default_version in snowflake.control is in sync with the new version.
Verify that the upgrade script snowflake--<old>-<new>.sql exists.
Thoroughly test everything, including the upgrade script.
Create the tag with git tag -a -m 'Version X.Y' vX.Y
Push the tag itself with git push --tags