Add host Art 12.0.0-beta4

Test: tools/test.py --no-internal --runtimes=dex-12.0.0
Bug: 197077780
Change-Id: I963f8d3c44ed73969420afe6a7e28a64d3a753ba
diff --git a/tools/test.py b/tools/test.py
index 9c35352..6553358 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -23,6 +23,7 @@
 
 ALL_ART_VMS = [
     "default",
+    "12.0.0",
     "10.0.0",
     "9.0.0",
     "8.1.0",