deps: V8: bump v8_embedder_string

Account for backported wasm exception handling correctness fixes.

Author: guybedford

common.gypi

@@ -38,7 +38,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.39',
+    'v8_embedder_string': '-node.40',
 
     ##### V8 defaults for Node.js #####