release: Zephyr 1.13rc2

Bump to 1.13rc2.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/VERSION b/VERSION
index 818aab4..be7c0da 100644
--- a/VERSION
+++ b/VERSION
@@ -2,4 +2,4 @@
 VERSION_MINOR = 13
 PATCHLEVEL = 0
 VERSION_TWEAK = 0
-EXTRAVERSION = rc1
+EXTRAVERSION = rc2