Add 31.0 to PLATFORM_SEPOLICY_COMPAT_VERSIONS

Bug: 189161483
Test: m selinux_policy
Change-Id: I48b681fb28c78ea9dca922f5fb58f19a940c1a51
diff --git a/core/config.mk b/core/config.mk
index d1746ef..5d71ee1 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -792,6 +792,7 @@
     28.0 \
     29.0 \
     30.0 \
+    31.0 \
 
 .KATI_READONLY := \
     PLATFORM_SEPOLICY_COMPAT_VERSIONS \