kunit: tool: remove unnecessary "annotations" import

The import was working around the fact "tuple[T]" was used instead of
typing.Tuple[T].

Convert it to use type.Tuple to be consistent with how the rest of the
code is anotated.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>