Bump version to 0.3.1

Make FIFOQueue, ActorQueue, and tests pass strict concurrency checking (

#13)

* Make FIFOQueue, ActorQueue, and tests pass strict concurrency checking

* Post-merge review feedback from #9 & #12

async -> enqueue. await -> enqueueAndWait (#12)

Rename AsyncQueue -> FIFOQueue. Create ActorQueue (#3)

* Rename AsyncQueue -> FIFOQueue. Create ActorQueue

* Create SemaphoreTests.swift to up coverage

* Simplify

* Get to 100% coverage

* Enable sending synchronous tasks to the ActorQueue

* Improve explanation of ActorQueue's ordering guarantee

* The queues are the antecedent

Co-authored-by: Michael Bachand <bachand.michael@gmail.com>

* Improve accuracy of ActorQueue description in README

Co-authored-by: Michael Bachand <bachand.michael@gmail.com>

* ActorQueue does not need to be Sendable

* Update comments

* documentation copy/pasta fix

* Disable sending synchronous tasks to the ActorQueue

* Better explain how test_async_startsExecutionOfNextTaskAfterSuspension works + simplify test

* Do not wait a runloop to test

* further test cleanup

* Write comments to explain the test

* Make wait() return whether it suspended

* Improve test_wait_suspendsUntilEqualNumberOfSignalCalls

* Better comments

* Better README documentation

* Remove duplicative label 'queue' from README discussion

* Eliminate race in test_wait_suspendsUntilEqualNumberOfSignalCalls()

* Move ActorQueue example to a doc comment

* Bump version and update README

* Simplify ActorExecutor

* Do not ship Semaphore. Use fewer 'await' calls in ActorExecutor

* Add link to Swift bug report

* Since we're renaming we should bump a major version (i.e. a minor version in beta semver)

* Delete SemaphoreTests.swift since it is no longer required

* Remove unnecessary '@mainactor' decoration on test

* Add test_async_retainsReceiverUntilFlushed() to ActorQueueTests to match FIFOQueueTests

* Better test name

* Make explicit that queue is deallocated in tests

* Update test_async_executesEnqueuedTasksAfterReceiverIsDeallocated() in ActorQueueTests to use an ActorQueue

* Accurate test method naming

* Remove unnecessary await

* Add swift tag to multi-line code examples

Co-authored-by: Michael Bachand <bachand.michael@gmail.com>

Replace actions/setup-ruby@v1 with ruby/setup-ruby@v1 (#4)