bug: metadata for updateApiKey should not be string but object

[swarnimarun]

https://github.com/PropelAuth/node-apis/blame/3e3c48ce5b732eb093d3bba79b38cc88ec15e294/src/api/endUserApiKeys.ts#L159

I am not sure if the request would even work if you give a string as metadata.
I always ts-ignore my way through but it should also be fixed here.