GYB won't create a new oauth2service.json when using --config-folder for custom location

I'm using this command to generate a backup of my Gmail account (personal account, not workspace/gsuite)
```
~/bin/gyb/gyb --config-folder ./Gmail- --action create-project --email @gmail.com
```

And the output is this
```
Creating project "Got Your Back Project"...
Checking project status...
Please go to:
https://console.cloud.google.com/start
and accept the Terms of Service (ToS). As soon as you've accepted the ToS popup, you can return here and press enter.

Creating project "Got Your Back Project"...
Checking project status...
enabling API drive.googleapis.com...
enabling API gmail.googleapis.com...
enabling API groupsmigration.googleapis.com...
enabling API iap.googleapis.com...
enabling API vault.googleapis.com...
Creating Service Account
ERROR: [Errno 2] No such file or directory: './Gmail-/oauth2service.json'
```

\* I've redacted the true email for obvious privacy reasons

Why won't it create the missing files it needs? Is this related to #345?