Remove some more resolutions in open server.

[Tbaut]

the server was throwing the following when doing any request:

(node:23761) UnhandledPromiseRejectionWarning: TypeError [ERR_INVALID_ARG_TYPE]: The "string" argument must be one of type string, Buffer, or ArrayBuffer. Received type object
at Function.byteLength (buffer.js:705:11)
at /home/thib/github/paritytech/polkassembly/chain-db-open-server/node_modules/apollo-server-express/src/expressApollo.ts:53:18
at processTicksAndRejections (internal/process/task_queues.js:94:5)
(node:23761) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:23761) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.