Package entryhuman contains the code to format slog.SinkEntry for humans.
const TimeFormat = "2006-01-02 15:04:05.000"
TimeFormat is a simplified RFC3339 format.
Fmt returns a human readable format for ent.
We never return with a trailing newline because Go's testing framework adds one automatically and if we include one, then we'll get two newlines. We also do not indent the fields as go's test does that automatically for extra lines in a log so if we did it here, the fields would be indented twice in test logs. So the Stderr logger indents all the fields itself.