Changes for version 0.13 - 2023-02-19

    • Swap all unit tests from `Test::More` to `Test2::V0`
    • Reomved test-time dependency on `Test::Identity`
    • t/30system.t should check that the impl actually provides a `->waitpid` method before using it
    • Insert a hacky "sleep 1" into the connect tests on MSWin32 in case that helps fix the test failures


Future-returning IO methods
base class for Future::IO implementations
system()-like methods for Future::IO
acceptance tests for Future::IO implementations