OHHTTPStubs with SPM in Xcode 12.5

### New Issue Checklist

- [x] I have tried with the latest version of OHHTTPStubs
- [x] I have read the [README](https://github.com/AliSoftware/OHHTTPStubs/blob/master/README.md)
- [x] I have read the [Using the right Swift Version of `OHHTTPStubs` for your project](https://github.com/AliSoftware/OHHTTPStubs#using-the-right-swift-version-of-ohhttpstubs-for-your-project) section
- [x] I have searched in the [existing issues](https://github.com/AliSoftware/OHHTTPStubs/issues?utf8=✓&q=is%3Aissue)
- [x] I have read [the OHHTTPStubs wiki](https://github.com/AliSoftware/OHHTTPStubs/wiki) to see if there wasn't a detailed page talking about my issue

### Environment

- version of OHHTTPStubs: 9.1.0
- integration method you are using:
* [ ] Cocoapods
* [ ] Carthage
* [ ] submodule
* [x] other (SPM)
- version of the tool you use: Xcode 12.5.1

### Issue Description

Stubs are being added but test condition block is never called. I am using Xcode 12.5.1 and thus Swift 5.4.2. I think I have an identical setup to #346 because I am also using UI tests without a host application.