fix: allow special characters on path parameters

[deivid11]

Parsing openapi3 files encodes parameter names, that causes the tests that uses this kind of parameters being skipped.

:rocket: Why this change?

openapi3 is not allowing url parameters with special characters, the endpoints are skipped.

:memo: Related issues and Pull Requests

https://github.com/apiaryio/dredd/issues/1908

:white_check_mark: What didn't I forget?

• [x] To write docs
• [x] To write tests
• [x] To put Conventional Changelog prefixes in front of all my commits and run npm run lint