Replace ruby plugin

[elliottmurray]

There have been some reported vulnerabilities with the bundled version of bundler.
E.g. https://www.cvedetails.com/cve/CVE-2016-7954/

Ruby engine, which wraps the ruby code we use, is no longer supported and so this vulnerability will not be fixed. The roadmap for Pact Python is to replace the Ruby code with a replacement being built in Rust. Will keep this open until that happens.

[YOU54F]

We still want to upgrade to the pact ffi, see #88

however v2.0.0 of pact-python has now been released, which includes traveling-ruby version 3.2 and has been expanded to include support for arm64 linux and arm64 macos.

Support is dropped for 32bit linux, hence the major version bump from 1.7.0 -> 2.0.0

see #342 for full details