Add back @types/zen-observable

Signed-off-by: Marcus Eide <eide@spotify.com>

plugins/shortcuts/package.json

@@ -24,6 +24,7 @@
     "@backstage/theme": "^0.2.5",
     "@material-ui/core": "^4.11.0",
     "@material-ui/icons": "^4.9.1",
+    "@types/zen-observable": "^0.8.2",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
     "react-hook-form": "^7.1.1",

yarn.lock

@@ -6937,7 +6937,7 @@
   resolved "https://registry.npmjs.org/@types/yup/-/yup-0.29.8.tgz#83db15735987db9fe5a38772a0fb9500e3c5bf39"
   integrity sha512-MBSp62AjB1KrSOI3gX9GekddXU5YYQAVA93+aSl78biBqoSzxg876aQY2KJK5Gnfbpqq7O2cadVX5kPAtBqIXw==
 
-"@types/zen-observable@^0.8.0":
+"@types/zen-observable@^0.8.0", "@types/zen-observable@^0.8.2":
   version "0.8.2"
   resolved "https://registry.npmjs.org/@types/zen-observable/-/zen-observable-0.8.2.tgz#808c9fa7e4517274ed555fa158f2de4b4f468e71"
   integrity sha512-HrCIVMLjE1MOozVoD86622S7aunluLb2PJdPfb3nYiEtohm8mIB/vyv0Fd37AdeMFrTUQXEunw78YloMA3Qilg==