This PR was created by Knope. Merging it will create a new release

### Breaking Changes

#### Removed the `update` command

The `update` command is no more, you can (mostly) replace its usage with
some new flags on the `generate` command.

If you had a package named `my-api-client` in the current working
directory, the `update` command previously would update the
`my_api_client` module within it. You can now _almost_ perfectly
replicate this behavior using `openapi-python-client generate
--meta=none --output-path=my-api-client/my_api_client --overwrite`.

The only difference is that `my-api-client` would have run `post_hooks`
in the `my-api-client` directory,
but `generate` will run `post_hooks` in the `output-path` directory.

Alternatively, you can now also run `openapi-python-client generate
--meta=<your-meta-type> --overwrite` to regenerate
the entire client, if you don't care about keeping any changes you've
made to the generated client.

Please comment on [discussion
openapi-generators#824](openapi-generators#824)
(or a new discussion, as appropriate) to aid in designing future
features that fill any gaps this leaves for you.

### Features

#### Added an `--output-path` option to `generate`

Rather than changing directories before running `generate` you can now
specify an output directory with `--output-path`.
Note that the project name will _not_ be appended to the
`--output-path`, whatever path you specify is where the
generated code will be placed.

#### Added an `--overwrite` flag to `generate`

You can now tell `openapi-python-client` to overwrite an existing
directory, rather than deleting it yourself before
running `generate`.

Co-authored-by: GitHub <[email protected]>