build: require Angular 21.2, the final 21.x minor line

Angular 21 is in long-term support.

Author: armando-navarro

src/package.json

@@ -27,10 +27,10 @@
   "author": "angular,firebase",
   "license": "MIT",
   "peerDependencies": {
-    "@angular/common": "^21.0.0",
-    "@angular/core": "^21.0.0",
-    "@angular/platform-browser": "^21.0.0",
-    "@angular/platform-server": "^21.0.0",
+    "@angular/common": "^21.2.0",
+    "@angular/core": "^21.2.0",
+    "@angular/platform-browser": "^21.2.0",
+    "@angular/platform-server": "^21.2.0",
     "rxjs": "~7.8.0",
     "firebase-tools": "^14.0.0 || ^15.0.0",
     "typescript": ">=5.8 <6.0"