fix(nestjs): declare rxjs peer dependency

Author: faizansaiyed123

packages/nestjs/package.json

@@ -57,7 +57,8 @@
   },
   "peerDependencies": {
     "@nestjs/common": "^8.0.0 || ^9.0.0 || ^10.0.0 || ^11.0.0 || ^12.0.0",
-    "@nestjs/core": "^8.0.0 || ^9.0.0 || ^10.0.0 || ^11.0.0 || ^12.0.0"
+    "@nestjs/core": "^8.0.0 || ^9.0.0 || ^10.0.0 || ^11.0.0 || ^12.0.0",
+    "rxjs": "^7.x"
   },
   "scripts": {
     "build": "run-p build:transpile build:types",