Try a slightly newer date

yuvipanda · yuvipanda · commit 3fb91c7f56b8 · 2023-06-09T23:44:54.000+05:30
diff --git a/tests/r/r3.6-rspm/runtime.txt b/tests/r/r3.6-rspm/runtime.txt
@@ -1 +1 @@
-r-3.6-2018-11-31
+r-3.6-2018-12-07
