Log Message:
(devel/R-callr) Updated 3.4.4 to 3.5.1 (make test fails at PDF creation)

# callr 3.5.1

* `callr::r_session` now handles large messages from the subprocess
  well (#168).

# callr 3.5.0

* callr can now pass the environment of the function to the subprocess,
  optionally. This makes it easier to call an internal function of a
  package in a subprocess. See the `package` argument of `r()`, `r_bg()`,
  `r_session$run()`, etc. (#147).