[test] Skip failing test

Bug: v8:12907
Change-Id: I8a6da86b4c88b5cfcc9bbb349841c422ac81b64e
No-Tree-Checks: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3667082
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80751}

test/mjsunit/mjsunit.status

@@ -400,6 +400,9 @@
   # BUG(v8:12561)
   'spread-large-map': [SKIP],
 
+  # BUG(v8:12907)
+  'temporal/plain-date-time-to-plain-time': [SKIP],
+
   # Flaky tests due to GC interferring with optimization.
   'compiler/regress-crbug-1323114': [SKIP],
 }],  # 'gc_stress'