Update the excluding message for Psych [ci skip]

nobu · nobu · commit 5389c9813b19 · 2022-08-16T13:49:28.000+09:00
diff --git a/test/excludes/Psych/TestDateTime.rb b/test/excludes/Psych/TestDateTime.rb
@@ -1 +1,4 @@
-exclude(:test_new_datetime, "Psych loses the start date")
+exclude(:test_new_datetime, <<MSG)
+Undefined behavior of YAML spec, no definitions for pre Gregorian dates.
+https://github.com/yaml/yaml/issues/69
+MSG
