Remove XCTest dependency so the lib could be used in the main target

[jverkoey]

For iteration purposes, it would be super nice to have a non-testing variation of the library that could be used for more interactive iterations on the use of the library.

As-is, attempting to include the library as a dependency in a non-test target results in the following linker errors:

Undefined symbol: XCTest.XCTFail(_: Swift.String, file: Swift.StaticString, line: Swift.UInt) -> ()
Undefined symbol: _OBJC_CLASS_$_XCTestExpectation

[jverkoey]

Splitting the XCTest logic out would also help set the library up for cleaner use with the new Swift Testing framework.

[nalexn]

Hey @jverkoey - that turned out to be quite easy to do - you could try that with the branch 0.10.3

[reesericci]

Just gave this a try by loading the commit directly, I'm not able to get my app to build with it included in my primary target.

Just a guess, but it seems that it might be related to the fact that XCTest is still specified in the podspec?