fix rate limiting

[OniriCorpe]

Problem

for now, all users are considered the same for rate limiting see: https://docs.ntfy.sh/config/#behind-a-proxy-tls-etc

Solution

set behind-proxy: true

PR Status

• [x] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable)

[yunohost-bot]

May the CI gods be with you!