Apollo-Server-Express using graphqlUploadExpress multiple files Question
I am having an issue when trying to  upload multiple files using Apollo-Server-Express (2.19.0) and graphqlUploadExpress (11.0.0) if I add multiple files it seems to be missing the `file` from anything after the 1st object in the array.

Any ideas as to what's causing the other items to fail?

**typeDef**
```
module.exports = gql`
    scalar Upload
    extend type Mutation {
        singleFileUpload(file: Upload!): File!
        multipleFileUpload(files: [Upload!]!): [File]   
    }

    type File {
        success: Boolean!
        message: String
        filename: String
        uuid: String
        localPath: String
        serverPath: String
        url: String
        mimetype: String
        encoding: String
    }
`;
```

**server.js**
```
app.use(graphqlUploadExpress({ maxFileSize: 50000000, maxFiles: 20}));
new ApolloServer({
    typeDefs,
    resolvers,
    context: ({ req, res }) => ({
      models,
      user: req.user,
      req,
      res
    }),
    uploads: false});
```
**resolver**
```
const processUpload = async (upload) => {
    const { filename, mimetype, encoding, createReadStream } = await upload.file;
    const { ext } = parse(filename);
    const typeDir = mimeTypeUploadDirectory(mimetype);
    const dateDir = submissionFolderDateStructure();
    const stream = createReadStream();
    const id = uuid();
    const uploadLocation = `${dateDir}/${typeDir}`;
    const baseLocation = `${UPLOAD_PATH}/${uploadLocation}`;
    const fileLocation = `${baseLocation}/${id}${ext}`;
    const localPath = join(__dirname, `src/../${fileLocation}`);
    const serverPath = `${uploadLocation}/${id}${ext}`;
    const url = `${URL}/${serverPath}`;

    mkdirp.sync(join(__dirname, `${baseLocation}`));

    return new Promise((resolve, reject) => {
        stream
            .on('error', (error) => {
                if (error) unlink(localPath);
                reject({
                    success: false,
                    message: error.message
                });
            })
            .pipe(createWriteStream(localPath))
            .on('finish', () => {
                resolve({
                    success: true,
                    message: null,
                    filename,
                    uuid: id,
                    localPath,
                    serverPath,
                    url,
                    mimetype,
                    encoding
                });
            });
    });

}
//TODO: add in auth stuff
const resolver = {
    Mutation: {
        singleFileUpload: async (_, { file }) => {
            return await processUpload(file);
        },
        //BUGFIX: items in the array after the first array are missing the file
        multipleFileUpload: async (_, { files }) => {
            let objArr = (await Promise.all(files)).map(processUpload);
            console.log(objArr);
            return objArr;
        }
    }
}
```
![mutation](https://user-images.githubusercontent.com/3682042/101786237-b1c23900-3acb-11eb-8ce7-9faa90d04d89.png)
![multiple_files_upload_debug](https://user-images.githubusercontent.com/3682042/101786253-b555c000-3acb-11eb-810c-78002f6f4fd7.png)
![returned_promises](https://user-images.githubusercontent.com/3682042/101786263-b850b080-3acb-11eb-9477-a4b8acf79dff.png)
Also if I look at the files coming in prior to sending them to my **processUpload** they look correct
![files_incoming](https://user-images.githubusercontent.com/3682042/101805374-adece180-3ae0-11eb-827d-f2d393e115d8.png)
