fpcentral: set "Accept-Encoding" header expected value assuming we are using https
In `fingerprint/acceptable/torbrowser70.json` we are expecting the value of the `Accept-Encoding` header to be `gzip, deflate`. This is true when fpcentral is deployed on http, but not on https:
https://trac.torproject.org/projects/tor/ticket/22656#comment:6
As https://fpcentral.tbb.torproject.org/ is using https, we should change it to `gzip, deflate, br`.
issue