Huge memory usage with a lot of parallel clients

[0xdeafbeef]

Previously

oha http://127.0.0.1:3000/todo/123 -c 1000 -z 60s -q 10000

will eat 5 gigs of ram after 1 minute.
Because closure which builds HTML was cloned on each request
https://github.com/tamasfe/aide/blob/master/crates/aide/src/redoc/mod.rs#L169