json: allow invalid RF3339 times

[X] I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
[X] This issue only relates to a single bug. I will open new issues for any other problems.

json marshaling time.Time results in an error for dates with more than 4 years ((too) strict RFC3339 times).

encoding/json/v2 "format"(?) might simplify this if it is added to the standard library.

kooky cli tool with -j option

c14297c

1.23.2

browserutils / kooky