Add tapir to TechEmpower/FrameworkBenchmarks

[kciesielski]

https://github.com/TechEmpower/FrameworkBenchmarks is an unified set of benchmarks comparing web frameworks across different criteria. It might be worthwile to add some variants of tapir there, as there are some "vanilla" Scala backends there already.

[adamw]

I think the Netty backend would be the best candidate (as it has the least intermediate layers)

[kciesielski]

I thought about it too, netty-future, possibly with jsoniter-scala.