Docker image espressif/idf-rust:all_1.68.0.0 does not contain espflash for CI

[georgik]

Docker image espressif/idf-rust:all_1.68.0.0 does not contain espflash which is useful for CI task when generating single file binaries:

cargo espflash save-image --chip esp32 --merge --release out.bin
error: no such command: `espflash`

        View all installed commands with `cargo --list`

Consider installing espflash during building image from binary.

Workaround:

cargo install cargo-espflash --git https://github.com/esp-rs/espflash.git

[SergioGasquez]

Closed by #204