Adding `withr` in `Suggests`

[chainsawriot]

withr::local_options() and withr::local_tempdir() are quite useful for writing tests with these "burner options" / "burner directories".

rJavaEnv/tests/testthat/test-java_valid_versions.R

Lines 22 to 25 in c78178c

	options(
	rJavaEnv.valid_versions_cache = fake_cache,
	rJavaEnv.valid_versions_timestamp = Sys.time()
	)