Revert "Add missing divider in upgrading-guide"
This reverts commit d8c745ca30.
Revert "Update history to reflect merge of #7521"
This reverts commit 7ee2e26d6c.
Revert "Upgrade WinTZ utility to use TZInfo-2.0"
This reverts commit 13cbef4221.
Lock use of `tzinfo` gem to v1.x