Implement a repro repo

[JP-Ellis]

more details to come, placeholder to keep track

110% - we might want to consider a repro repo they can fork, or how they can add their example say to your example suite, and have the ci system run it for a repro, that way it is contained within the maintainers domain (of pact-python) and if the examples are useful they can remain

Originally posted by @YOU54F in #390 (comment)