Add layouts to Eta example

[nebrelbug]

Details

As of https://github.com/eta-dev/eta/releases/tag/v1.9.0, Eta supports layouts. I thought it would be helpful to update the Eta example to use layouts.

CheckList

• [x] Has been tested (where required) before merge to main.

[github-actions[bot]]

Benchmark results

PR to merge add-eta-layouts 8a2b92053a5a0074ce0501bdf244c2f93e54f5ee -> main

``` 1 middleware 6478.54 RPS 5 middleware 6649.42 RPS 10 middleware 6738.65 RPS 15 middleware 6371.06 RPS 20 middleware 6180.91 RPS 30 middleware 5847.40 RPS 50 middleware 5885.74 RPS 100 middleware 5234.54 RPS ```

[asos-craigmorten]

Nice one @nebrelbug 🚀