Upgrade @types/zen-observable to 0.5.4

[ChenRoth]

current version conflicts @types/node's newly added readonly modifier for the observable type
Referencing this issue: DefinitelyTyped/DefinitelyTyped#26239 (comment)

[lukeify]

In the meantime, if you're using yarn, use the resolutions block in package.json to force 0.5.4 for zen-observable.

"resolutions": {
    "@types/zen-observable": "0.5.4"
}

[JohannesHoppe]

This should be merged with highest priority!

Meanwhile:

npm i @types/zen-observable@0.5.4

did the same trick for me (NPM user).

[BPScott]

Fixed in #681.

Just waiting on a release of apollo-link-polling and apollo-link-retry

[JoviDeCroock]

This is fixed so closing this