added a missing newline at the end of the file

Author: dietmarkuehl

tests/beman/execution/issue-186.test.cpp

@@ -31,4 +31,4 @@ int main() {
                 | ex::let_value([](move_only_type v) noexcept { return ex::just(v.val * 3); }); // move_only_type
     auto [ret2] = ex::sync_wait(std::move(snd2)).value();
     assert(ret2 == 6);
-}
+}