various fixes

[bnkai]

Recent stash versions had some code changes so a fix was needed.

• Fixed the graphql image upload part (main issue)
• Added user agent to the headers (feel free to rename, as i was too lazy to find a proper name)
• Added some requests tweaks
• Added a sleep of 1s between most of the metadataapi requests (Should be equivalent to max 60 reqs / min, feel free to adjust)
• Upped pilllow version in requirements so that the script runs with latest python3 version
• Added authorization via API Key using a configuration setting