Add failsafe.dev

[Andrej Fink]

It is much beyond my abilities to make a proper Pull Request to this repository :-(

I suggest you to add directly after [Resilience4j], its modern zero-dependency alternative "Failsafe" with a Vert.x integration example:

* [Failsafe](https://failsafe.dev/) - Failsafe is a lightweight, *zero-dependency* library for handling failures in Java 8+. Concise API. Integration with libraries that use their own schedulers for async executions, such as Akka or Vert.x. [Vert.x example](https://github.com/failsafe-lib/failsafe/blob/master/examples/src/main/java/dev/failsafe/examples/VertxExample.java)

OR as commit

[Thomas Segismont]

Closed in #184 , thanks