deps: V8: bump v8_embedder_string for 0e21c1e

0e21c1e has landed without a proper
v8_embedder_string bump, this is a follow-up fix.

PR-URL: #31096
Refs: 0e21c1e
Refs: #31007
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

common.gypi

@@ -39,7 +39,7 @@
 
     # 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.25',
+    'v8_embedder_string': '-node.26',
 
     ##### V8 defaults for Node.js #####