src: update NODE_MODULE_VERSION to 67

Major V8 updates are usually API/ABI incompatible with previous
versions. This commit adapts NODE_MODULE_VERSION for V8 7.0.

Refs: https://github.com/nodejs/CTC/blob/master/meetings/2016-09-28.md

PR-URL: #22754
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_version.h

@@ -110,10 +110,11 @@
  * V8 6.7: 64
  * V8 6.8: 65
  * V8 6.9: 66
+ * V8 7.0: 67
  *
  * More information can be found at https://nodejs.org/en/download/releases/
  */
-#define NODE_MODULE_VERSION 66
+#define NODE_MODULE_VERSION 67
 
 // the NAPI_VERSION provided by this version of the runtime
 #define NAPI_VERSION  3