Pact Foundation

To test generators in compatibility suite, I have to use <https://github.com/pact-foundation/pact-reference/blob/master/rust/pact_ffi/IntegrationJson.md|Integration Json>. But there are some difficulties:
• `pact:generator:type` is only optional, `pact:matcher:type` is still required
• Set `pact:matcher:type` to `null` or `integer` is the easiest way
• If I set `pact:matcher:type` to something like `type` , I need to also set `value` , which prevent `pact:generator:type` from working
• But I got these errors `Could not generate a random decimal from null`
• Other generator like `date` , `time` , `datetime` or `boolean` works fine because they don't validate the `value`
• Is this change a good idea: <https://github.com/pact-foundation/pact-reference/compare/master...tienvx:pact-reference:force-generator-works-regardless-value-type?expand=1> 

I found a very similar block of code here <https://github.com/pact-foundation/pact-reference/blob/master/rust/pact_models/src/generators/mod.rs#L854>, so I think it's fine to do like that as well.

Created PR anyway <https://github.com/pact-foundation/pact-reference/pull/335>