Go versions higher than 1.15 will throw 'no required modules' error for crypto/chacha20poly1305

When using go version higher than 1.15, we see the following errors:

_go_benchmarks.go:16:2: no required module provides package golang.org/x/crypto/chacha20poly1305: go.mod file not found in current                  directory or any parent directory; see 'go help modules'_

The reason is that golang/crypto has release version only upto 1.15. Even if we try to use a golang/crypto version higher than that (ex. [internal-branch.go1.17-vendor] when using say go 1.17) then we get the following error:

_package command-line-arguments
        imports golang.org/x/crypto/chacha20poly1305
        golang/go/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go:11:2: use of internal package vendor/golang.org/            x/crypto/internal/subtle not allowed_

Ideally the issue is due to the way go.mod is defined and how the golang/crypto doesn't have released versions for versions higher than 1.15.

As an interim workaround, the cf_benchmark repository was last updated 2 years ago, so we found go-1.15 to be the most apt version to use because it also has the compatible golang/crypto - 1.15 release version.

I will submit a PR to may be reflect the go version in the cf_benchmark README.