py/persistentcode: Bump .mpy sub-version.

This is required because the previous commit changed the .mpy native ABI.

Signed-off-by: Damien George <damien@micropython.org>

py/persistentcode.h

@@ -35,7 +35,7 @@
 // set) must also match MPY_SUB_VERSION. This allows 3 additional updates to
 // the native ABI per bytecode revision.
 #define MPY_VERSION 6
-#define MPY_SUB_VERSION 1
+#define MPY_SUB_VERSION 2
 
 // Macros to encode/decode sub-version to/from the feature byte. This replaces
 // the bits previously used to encode the flags (map caching and unicode)