Log Message:
py-pip-audit: update to 2.2.1.

## [2.2.1] - 2022-05-02

### Fixed

* A bug introduced with a previous fix to version parsing
  ([#263](https://github.com/trailofbits/pip-audit/pull/263)) was
  fixed ([#264](https://github.com/trailofbits/pip-audit/pull/264))

## [2.2.0] - 2022-05-02

### Added

* CLI: The `--output` option has been added, allowing users to specify
  a file to write output to. The default behavior of writing to `stdout`
  is unchanged ([#262](https://github.com/trailofbits/pip-audit/pull/262))

### Fixed

* Vulnerability sources: A bug caused by insufficient version normalization
  was fixed ([#263](https://github.com/trailofbits/pip-audit/pull/263))