executor: aborts on multiple panics

```rust use std::time::Duration; use compio_runtime::time::sleep; #[test] #[should_panic] fn panic_spawn() { compio_runtime::Runtime::new().unwrap().block_on(async { let _handle = compio_runtime::spawn(async { sleep(Duration::from_millis(100)).await; panic!("test panic in spawn"); }); sleep(Duration::from_millis(100)).await; panic!("another panic"); }) } ``` This code should panic but actually aborts.