Add ErasedChild #45

Job	Run time
Fmt check	10s
Test on macos with Rust stable (feat: default)	23s
Test on macos with Rust stable (feat: with-tokio)	45s
Test on macos with Rust 1.68.0 (feat: default)	5m 27s
Test on macos with Rust 1.68.0 (feat: with-tokio)	4m 42s
Test on ubuntu with Rust stable (feat: default)	41s
Test on ubuntu with Rust stable (feat: with-tokio)	15s
Test on ubuntu with Rust 1.68.0 (feat: default)	5m 37s
Test on ubuntu with Rust 1.68.0 (feat: with-tokio)	3m 26s
Test on windows with Rust stable (feat: default)	1m 42s
Test on windows with Rust stable (feat: with-tokio)	1m 44s
Test on windows with Rust 1.68.0 (feat: default)	6m 56s
Test on windows with Rust 1.68.0 (feat: with-tokio)	4m 49s
	36m 37s

Provide feedback