build: update pnpm to v12

See associated pull request for more information.

Author: angular-robot

package.json

@@ -28,12 +28,12 @@
     "type": "git",
     "url": "git+https://github.com/angular/angular-cli.git"
   },
-  "packageManager": "pnpm@11.25.0",
+  "packageManager": "pnpm@12.3.4",
   "engines": {
     "node": "^22.22.3 || ^24.15.0 || >=26.0.0",
     "npm": "Please use pnpm instead of NPM to install dependencies",
     "yarn": "Please use pnpm instead of Yarn to install dependencies",
-    "pnpm": "11.25.0"
+    "pnpm": "12.3.4"
   },
   "author": "Angular Authors",
   "license": "MIT",