build: update main branch to v20 (#30524)

Bumps the main branch to target v20.

Author: crisbeto

package.json

@@ -54,7 +54,7 @@
     "ci-notify-slack-failure": "node --no-warnings=ExperimentalWarning --loader ts-node/esm/transpile-only scripts/circleci/notify-slack-job-failure.mts",
     "prepare": "husky"
   },
-  "version": "19.3.0-next.0",
+  "version": "20.0.0-next.0",
   "dependencies": {
     "@angular/animations": "^19.1.3",
     "@angular/common": "^19.1.3",