Apollo Server v4 issue - BadRequestError: POST body missing, invalid Content-Type, or JSON object has no keys.
I have updated both Apollo Server to v4 and Apollo Client to v3 and am getting an error on the server, the v3 client works with the old v3 server. 

Test Example :-
https://github.com/AaronNGray/apollo-v4-upload-test.git

```
BadRequestError: POST body missing, invalid Content-Type, or JSON object has no keys.
at new GraphQLErrorWithCode (file:///C:/Users/aaron/Test/apollo-v4-express-upload-test/api/node_modules/@apollo/server/dist/esm/internalErrorClasses.js:7:9)
at new BadRequestError (file:///C:/Users/aaron/Test/apollo-v4-express-upload-test/api/node_modules/@apollo/server/dist/esm/internalErrorClasses.js:75:9)
at runHttpQuery (file:///C:/Users/aaron/Test/apollo-v4-express-upload-test/api/node_modules/@apollo/server/dist/esm/runHttpQuery.js:75:23)
at runPotentiallyBatchedHttpQuery (file:///C:/Users/aaron/Test/apollo-v4-express-upload-test/api/node_modules/@apollo/server/dist/esm/httpBatching.js:34:22)
at ApolloServer.executeHTTPGraphQLRequest (file:///C:/Users/aaron/Test/apollo-v4-express-upload-test/api/node_modules/@apollo/server/dist/esm/ApolloServer.js:515:26)
```