fix(platform-browser): add missing peerDependency on `@angular/animations` (#35949)

`@angular/platform-browser/animations` has a dependency on `@angular/animations` however, this is not listed in `peerDependencies`

With this change we add this package as an optional peerDependency as it's only required when using the `@angular/platform-browser/animations` entrypoint.

Fixes #35888

PR Close #35949

packages/platform-browser/package.json

@@ -13,10 +13,16 @@
   "author": "angular",
   "license": "MIT",
   "peerDependencies": {
+    "@angular/animations": "0.0.0-PLACEHOLDER",
     "@angular/core": "0.0.0-PLACEHOLDER",
     "@angular/common": "0.0.0-PLACEHOLDER",
     "tslib": "^1.10.0"
   },
+  "peerDependenciesMeta": {
+    "@angular/animations": {
+      "optional": true
+    }
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/angular/angular.git",