Switch to stability attribute

(cherry picked from commit de7ef3b)

Author: gilles-duboscq

mx.graalpython/mx_graalpython.py

@@ -1450,7 +1450,7 @@ def verify_ci(dest_suite, common_ci_dir="ci_common", args=None, ext=('.jsonnet',
         'graalpython:GRAALPYTHON_GRAALVM_LICENSES',
     ],
     priority=5,
-    supported=False,
+    stability="experimental",
 ))
 
 
@@ -1491,7 +1491,7 @@ def verify_ci(dest_suite, common_ci_dir="ci_common", args=None, ext=('.jsonnet',
         )
     ],
     priority=5,
-    supported=False,
+    stability="experimental",
 ))