Log message:
(sysutils/R-processx) Updated 3.4.1 to 3.4.5

# processx 3.4.5

* New options in `pty_options` to set the initial size of the pseudo
  terminal.

* Reading the standard output or error now does not crash occasionally
  when a `\n` character is at the beginning of the input buffer (#281).

# processx 3.4.4

* processx now works correctly for non-ASCII commands and arguments passed
  in the native encoding, on Windows (#261, #262, #263, #264).

* Providing multiple environment variables now works on windows (#267).

# processx 3.4.3

* The supervisor (activated with `supervise = TRUE`) does not crash
  on the Windows Subsystem on Linux (WSL) now (#222).

* Fix ABI compatibility for pre and post R 4.0.1 versions. Now CRAN
  builds (with R 4.0.2 and later 4.0.x) work well on R 4.0.0.

* Now processx can run commands on UNC paths specified with
  forward slashes: `//hostname/...` UNC paths with the usual
  back-slashes were always fine (#249).

* The `$as_ps_handle()` method works now better; previously it
  sometimes created an invalid `ps::ps_handle` object, if the system
  clock has changed (#258).

# processx 3.4.2

* `run()` now does a better job with displaying the spinner on terminals
  that buffer the output (#223).

* Error messages are now fully printed after an error. In non-interactive
  sessions, the stack trace is printed as well.

* Further improved error messages. Errors from C code now include the
  name of the C function, and errors that belong to a process include the
  system command (#197).

* processx does not crash now if the process receives a SIGPIPE signal when
  trying to write to a pipe, of which the other end has already exited.

* processx now to works better with fork clusters from the parallel
  package. See 'Mixing processx and the parallel base R package' in the
  README file (#236).

* processx now does no block SIGCHLD by default in the subprocess,
  blocking potentially causes zombie sub-subprocesses (#240).

* The `process$wait()` method now does not leak file descriptors on
  Unix when interrupted (#141).

Log message:
Add missing dependency on devel/R-R6.