fix(schematics): accept firebase-tools 15 in the peer range (#3702)

The optional firebase-tools peerDependency was capped at ^14.0.0, which
excludes the current major (15.x). The ng add version check already
accepts anything >= 14.0.0 and the schematic runs fine on 15.x, so the
narrow range only produces spurious peer-dependency warnings for users
on the current CLI.

Author: armando-navarro

src/package.json

@@ -29,7 +29,7 @@
     "@angular/platform-browser-dynamic": "^21.0.0",
     "@angular/platform-server": "^21.0.0",
     "rxjs": "~7.8.0",
-    "firebase-tools": "^14.0.0"
+    "firebase-tools": "^14.0.0 || ^15.0.0"
   },
   "peerDependenciesMeta": {
     "firebase-tools": { "optional": true },