end-to-end tests leave ports open if tests fail

[kh-aeros]

When I run cargo leptos end-to-end, if a test fails, when I attempt to run again, it fails to serve the application.

Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.20s
       Cargo finished cargo build --package=my-app --bin=my-app --no-default-features --features=ssr
     Serving at http://0.0.0.0:8000
thread 'main' panicked at code/rust/ui/my-app/src/main.rs:26:63:
called `Result::unwrap()` on an `Err` value: Os { code: 98, kind: AddrInUse, message: "Address already in use" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace