https://pre-commit.com/#confining-hooks-to-run-at-certain-stages

feat(pre-commit): Improve (/limit) default set of stages to run in

Make `typos` the `ENTRYPOINT` rather than cmd, and output `--help` by
default.

Provides for better UX when running the image without arguments, and
facilitates just passing args to `typos` instead of having to repeat the
command name.

BREAKING CHANGE: `typos` must no longer given as the first argument
when running the Docker image, as it is the default `ENTRYPOINT` now.

`rust:1.65.0` is based on Bullseye, and at time of writing the binary
built on it does not work on Buster:

```
$ docker build -t typos . && docker run --rm -it typos typos -V
typos: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.29' not found
       (required by typos)
```

Use `bullseye` explicitly to make the correspondence with the final
image clear, and remove explicit Rust version as it does not seem that
important, and the final runtime image version is what it is at the time
too.

Makes it overridable from CLI, and just one place to update.

fix: Docker/Debian version sync

feat: Improve Docker image entry