Add Express 5 (Beta) benchmark

[rafaell-lycan]

Hello,

One of the things that can be improved regarding this benchmark would also be targeting the beta version of Express which has been under development since last year for a better view of what can be done regarding performance improvements on the next big release.

No major changes on the test suit itself, just a new file needed using npm install express@5.0.0-beta.1 --save

[Eomm]

Thanks for reporting!
Would you like to send a Pull Request to address this issue?