`verifySignature` does not work when the caller is not running in UTC

[kevcodez]

For the webhook timestamp verification, the current date and the date from the webhook is compared. The X-Orb-Timestamp header does not include a timezone, so initializing a date using new Date will use the local timezone, instead of UTC:

orb-node/src/resources/webhooks.ts

Line 96 in 3ef8638

const timestamp = new Date(msgTimestamp);

When your server is running in a non-UTC timezone, this will lead to multiple hours of differences between the timestamp and the current date, given the wrongly used timezone.

Two possible solutions:

• Include the timezone in the x-orb-timestamp header (basically breaking change)
• Assume UTC timezone (append Z when using new Date or use a different way to create the date)