Rand.Seed is deprecated and global rand functions are auto seeded since go 1.20

Rand.Seed is used in the httpbackend Init method.

[https://go.dev/doc/go1.20#library](https://go.dev/doc/go1.20#library
)
[https://github.com/golang/go/issues/54880](https://github.com/golang/go/issues/54880
)
