I'm not 100% sure -- this is what my `Embed.toml` looks like:
```toml
[default.general]
chip = "STM32F411CEUx"

[default.rtt]
enabled = true

[env]
DEFMT_LOG = "trace"
```

I don't see anything in the [config template](https://github.com/probe-rs/probe-rs/blob/master/probe-rs/src/bin/probe-rs/cmd/cargo_embed/config/default.toml) that indicates encoding