Define expected package manager

For some reason, this seems to be always generated
now every time I run yarn in the repo so we may as
well set it.

https://nodejs.org/api/packages.html#packagemanager

package.json

@@ -65,5 +65,6 @@
     "ts-node": "^10.1.0",
     "typechain": "^8.0.0",
     "typescript": "^4.5.2"
-  }
+  },
+  "packageManager": "[email protected]"
 }