(devel/R-pkgload) Updated 1.3.3 to 1.3.4

# pkgload 1.3.4

* On load, pkgload now sets `PKGLOAD_PARENT_TEMPDIR` to the temporary
  directory used in the current process. This provides a convenient place
  to cache results for functions used in subprocesses (e.g. `devtools::test()`,
  `devtools::document()`).

* Fixes for Debian packaging.

(mef)