How can I write POSIXct columns with milliseconds using vroom::vroom_write()?

I can use format() before saving to "render" the time as character (see below), but I wonder if there's a neater way, e.g., by setting some option?

# Example data
df = data.frame(time = Sys.time() + runif(5, 0, 10^6))

# Convert POSIXct cols
POSIXct_cols = sapply(df, \(x) "POSIXct" %in% class(x))
df[POSIXct_cols] = lapply(df[POSIXct_cols], \(x) format(x, "%Y-%m-%d %H:%M:%OS3")))

# Save
vroom::vroom_write(df, "df.csv")