By adding merge tags {now} and {yesterday}, we make it possible to use [gvlogic] to check for expiration, distinguish between past and future events, etc.

• {today} exists: it's the current date in the site's timezone. Please ensure that it works.

Add:

• {now} a timestamp in local timezone
• {yesterday}: {today} -1 day
• Support :format Merge Tag modifiers for {now}, {today}, and {yesterday}
• Unit tests for this functionality

Re: https://docs.gravitykit.com/article/446-highlighting-entries-about-to-expire