chore(internal/librarian/nodejs): update node generator (#6575)

Update nodejs generator to
[v4.12.1](https://github.com/googleapis/google-cloud-node/releases/tag/gapic-generator-v4.12.1).

Author: JoeWang1127

internal/librarian/nodejs/librarian.yaml

@@ -19,9 +19,9 @@ language: nodejs
 tools:
   pnpm:
     - name: gapic-generator-typescript
-      version: "gapic-generator-v4.12.0"
-      package: "https://github.com/googleapis/google-cloud-node/archive/gapic-generator-v4.12.0.tar.gz"
-      checksum: "7db96e31b8c6ac15d40e92654a731ec7aa2b0a3425708ac68369b374688112e8"
+      version: "gapic-generator-v4.12.1"
+      package: "https://github.com/googleapis/google-cloud-node/archive/gapic-generator-v4.12.1.tar.gz"
+      checksum: "477e4a9b3442457667846bd5c629d1c059e7caf2d5a3ebce95da626a2d42ea80"
       build:
         - "pnpm install"
         # tsc only compiles TypeScript; the generator also needs templates/