Fix ttgo feature

[pyaillet]

Without this, a cargo c --features "ttgo" fails with:

error[E0308]: mismatched types
   --> src/main.rs:809:5
    |
768 | ) -> Result<()> {
    |      ---------- expected `std::result::Result<(), anyhow::Error>` because of return type
...
809 |     led_draw(&mut display.cropped(&Rectangle::new(top_left, size)))
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `anyhow::Error`, found enum `st7789::Error`
    |
    = note: expected enum `std::result::Result<_, anyhow::Error>`
               found enum `std::result::Result<_, st7789::Error<EspError>>`

I included fixes for heltec, kaluga, ...

[pyaillet]

Sorry for the missing cargo fmt. I should add a git pre-commit hook I guess :\