Remove unused rxjs-spy dev dependency

Author: tdonohue

package-lock.json

@@ -229,7 +229,6 @@
     "postcss-loader": "^4.0.3",
     "postcss-preset-env": "^7.4.2",
     "rimraf": "^3.0.2",
-    "rxjs-spy": "^8.0.2",
     "sass": "~1.80.3",
     "sass-loader": "^12.6.0",
     "sass-resources-loader": "^2.2.5",