Fix set_permissions test on Windows (no execute bit support)

Windows does not support the execute permission bit, so chmod 777
results in mode 666. Allow both values in the test assertion.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bschilder

tests/testthat/test-set_permissions.R

@@ -28,8 +28,8 @@ test_that("set_permissions sets permissions on a temp file", {
   set_permissions(f, verbose = FALSE)
 
   info_after <- file.info(f)
-  ## After set_permissions the file should have 777
-  testthat::expect_equal(as.character(info_after$mode), "777")
+  ## After set_permissions the file should have 777 (Unix) or 666 (Windows, no execute bit)
+  testthat::expect_true(as.character(info_after$mode) %in% c("777", "666"))
 })
 
 test_that("set_permissions works with is_folder=TRUE on a temp directory", {