Skjold

Bugfix / Maintenance release.

**Changes**
- Update `README.md`. Fix for wrong option name in documentation. Thanks endwaa ! (7)
- Properly handle PyUp `$meta` field when populating advisories from cache. (8)
- Set `pre-commit` default python interpreter from `3.7` to `3.8`.
- Start testing against `3.9.0-rc2`.
- Use latest `actions/checkoutv2` and `actions/setup-pythonv2` in `test` workflow.
- Update pre-commit hook (`v2.5.0` -> `v3.2.0`) and black hook (`19.10b0` -> `20.8b1`) repositories.
- Updated dependencies.

Feature release.

**Changes**
- Determine _severity_ (`Base Score`) using CVSS 2.0 / CVSS 3.x vectors from _Gemnasium_ records.
- Print _Warning_ to `stderr` when failing to extract _package_ and pinned _version_ from a `requirements.txt`-formatted file. Thanks brondsem! (3)
- Simplify pre-commit instructions. Thanks asottile ! (6)
- Updated dependencies.

Bugfix release.

**Changes**
- Fix 4: CLI crashes when given _unknown_ severity level. Thanks brondsem! (PR 5)
- Use _red_ instead of _yellow_ for results with `UNKNOWN` severity from _PyUP_ and _Gemnasium_ where skjold is (currently) not able to extract or calculate the severity of the item.
- Colorize results with `UNKNOWN` severity *red* instead of *yellow*.
- Extend CLI coloring dictionary to cover CVSS v2.0 and CVSS v3.0 severity levels.
- Set returned severity of PyUP results to 'UNKNOWN' as severity is not present in safety-db.
- Start handling comments in `requirements.txt`. Thanks brondsem!
- Add bug tracker and changelog URLs to `pyproject.toml`.
- Update `README.md`. Thanks brondsem!
- Extended tests.

Bugfix release.

**Changes**
- Support for _Python 3.6_.
- Type annotations for _tests_.

**Documentation**
- Fixed broken links in _README.md_. Thanks ghtyrant!

Bugfix release.

**Changes**
- Fix installation issue with `.pre-commit-hooks.yaml` setup.
- Update _README.md_ (Typos, Anchors).

Initial release.

**Changes**
- Support for [PyUP.io safety-db](https://github.com/pyupio/safety-db), [GitHub Advisory Database](https://github.com/advisories), and [GitLab gemnasium-db](https://gitlab.com/gitlab-org/security-products/gemnasium-db).
- Added [pre-commit](https://pre-commit.com/) hook.
- Support for `json` as additional output format.
- Support reading `poetry.lock` files (_poetry_).
- Support reading `Pipfile.lock` files (_pipenv_).
- Support for reading _frozen_ requirements.txt from file or `stdin` (e.g. via `pip freeze`.
- Basic caching.
- Configuration via `tools.skjold` in `pyproject.toml`.