src: unset NODE_VERSION_IS_RELEASE

When 53b8c51 was cherry-picked into
`master`, `NODE_VERSION_IS_RELEASE` was accidentally set to `1` as well.

PR-URL: nodejs#14005
Reviewed-By: Rod Vagg <rod@vagg.org>

Author: addaleax

src/node_version.h

@@ -26,7 +26,7 @@
 #define NODE_MINOR_VERSION 0
 #define NODE_PATCH_VERSION 0
 
-#define NODE_VERSION_IS_RELEASE 1
+#define NODE_VERSION_IS_RELEASE 0
 
 #ifndef NODE_STRINGIFY
 #define NODE_STRINGIFY(n) NODE_STRINGIFY_HELPER(n)