Consider stripping binaries

Hi,

I tested this
```bash
cargo build --release --bins --features selfupdate
```

`strip` disabled:
juliainstaller - 7.8MB
julialauncher - 4MB
juliaup - 7.8MB

`strip` enabled:
juliainstaller - 4.4MB
julialauncher - 2MB
juliaup - 4.5MB

You can enable strip on release by adding `strip = true` to `profile.release`.

Locate the Cargo release profile configuration and first reproduce the supplied `cargo build --release --bins --features selfupdate` command. Enable release stripping as proposed, then verify the build succeeds and compare the resulting juliainstaller, julialauncher, and juliaup sizes with the reported reductions.

Written by the indexing model from the issue text.