dplyr 1.0.0 breaks pkgattrs::write_pkg_api function

[IndrajeetPatil]

This is the traceback I see and the breakage has to do with this issue: tidyverse/dplyr#4895

> rlang::last_error()
<error/rlang_error>
`summarise()` argument `lines` errored.
i `lines` is `n()`.
i The error occured in group 1: fn_name = "bartlett_message", subtype = "blank".
x could not find function "n"

Backtrace:
  1. pkgattrs::write_pkg_api(getwd(), filename = "API")
  2. pkgattrs::pkg_api(...)
  3. pkgattrs::pkgattrs(...)
  4. base::seq(nrow(pkg_locations))
 12. purrr::map_df(...)
 13. purrr::map(.x, .f, ...)
 14. pkgattrs:::.f(.x[[i]], ...)
  8. pkgattrs:::get_fn_lines_info(...)
  8. dplyr::group_by(., fn_name, subtype)
 15. dplyr::summarize(., lines = n())
 26. dplyr:::summarise_cols(.data, ...)
 27. base::tryCatch(...)
 28. base:::tryCatchList(expr, classes, parentenv, handlers)
 29. base:::tryCatchOne(...)
 30. value[[3L]](cond)
 31. dplyr:::stop_eval_tidy(e, index = i, dots = dots, fn = "summarise")
 32. dplyr:::stop_dplyr(index, dots, fn, "errored", x = conditionMessage(e))