Update ENV variables in uploadRouter

[JusticeMatthew]

When labs33 had this project we needed to update the name of the AWS ENV variables in our .env files to this format:

AWS_ACCESS_KEY_ID
AWS_SECRET_ACCESS_KEY

To match what the AWS docs require

This change never made it into the uploadRouter so it still has the old ENV variable names as shown here:

These variables will need to be corrected in the uploadRouter

These variables should also be checked on Heroku to ensure their naming conventions match and that their values are still good

I think these changes will fix the upload endpoint for the deployed site 👍