fix: drop gzip support, improve performance. (#1854)

BREAKING CHANGE

Not gzipping the output more than doubles the throughput for a simple "do nothing" RPC function.

Postgrest's gzip support was surprisingly slow, lacked in configurability, was undocumented and untested.

It was possible to achieve this before by not sending `Accept-Encoding: gzip`, but that turned into a bit of an undocumented gotcha. Most browsers do send it and by default a proxy pass would forward this header. Better to not support gzip at all, further focusing on ensuring Postgrest is a minimal layer over Postgres.

Nginx, or whatever proxy, provides critical options such as min length, vary headers and so forth, and will likely have much better performance as well.

src/PostgREST/Middleware.hs

@@ -116,7 +116,6 @@ pgrstFormat minStatus date req status responseSize =
 pgrstMiddleware :: LogLevel -> Wai.Application -> Wai.Application
 pgrstMiddleware logLevel =
     logger
-  . Wai.gzip Wai.def
   . Wai.cors corsPolicy
   . Wai.staticPolicy (Wai.only [("favicon.ico", "static/favicon.ico")])
   where