ARROW-8217: [R] Unskip previously failing test on Win32 in test-datas…

…et.R from ARROW-7979

Neal found that the test passed in a debug build, let's see if the test still fails on master

Closes #6799 from wesm/unskip-failing-r-test

Authored-by: Wes McKinney <wesm+git@apache.org>
Signed-off-by: Wes McKinney <wesm+git@apache.org>

r/tests/testthat/test-dataset.R

@@ -174,9 +174,6 @@ test_that("IPC/Arrow format data", {
     dim(ds),
     "Number of rows unknown; returning NA"
   )
-  # This causes a segfault on Windows R 32-bit following ARROW-7979
-  # TODO: fix me
-  skip_on_os("windows")
   expect_equivalent(
     ds %>%
       select(string = chr, integer = int, part) %>%