removes throws from waitForExpectations

* disables swiftSettings from targets due to unsafe settings
* removes `try` from all of the tests for the wait calls

enabled concurrency warnings and fixes every warning

fixes behavior of inverted expectations which can fulfill after timeout

enables concurrency warnings for tests

* fixes concurrency warnings in unit tests
* enables thread sanitizer

revised public API to integrate more closely with XCTest

lowers Swift tools version to 5.6

init