Adding bluetooth apex and min_sdk_version

Bug: 206121418
Test: Compile
Change-Id: I59dbd7a2b4758be4b90acfd419112e8b9e259219
diff --git a/bluetooth/audio/aidl/Android.bp b/bluetooth/audio/aidl/Android.bp
index 5107240..52671b8 100644
--- a/bluetooth/audio/aidl/Android.bp
+++ b/bluetooth/audio/aidl/Android.bp
@@ -47,6 +47,7 @@
                 "//apex_available:platform",
                 "com.android.bluetooth",
             ],
+            min_sdk_version: "31",
         },
     },
 }