Fix problem when Connect user writes a new pin with a different Connect user name

[juliasilge]

If I try to write a new pin to Connect using code like:

library(pins)
b <- board_connect()
b |> pin_write(1:10, "katie.masiello/this-is-not-really-katie")

the write succeeds and I get results like these:

The code for the HTML preview shows Katie's username, but that code will not work.

[juliasilge]

Related to #797