Two changes here:
1. Update `.prettierignore` to cover all folders named `flow-typed` instead of individually enumerating each `flow-typed` folder in the repo.
2. Revert the Prettier changes to `services/electron-update-server/flow-typed/npm/express_v4.17.x.js`. This is to make it easier to diff against upstream changes, and to make sure it matches the libdef we have in the `keyserver` folder.
> NOTE: CI will fail on this diff. I considered the possibility of fixing Flow errors BEFORE upgrading Flow, but it wasn't possible... in some cases, the fixes to support the new version of Flow caused errors in the old version. I could have hidden these type errors with `$FlowFixMe` lines and then later revert those, but that seemed like too much busy work.