0.37.0 - 2020-12-08
-------------------

- Remove support for CentOS 6 and Python 2.6 (remove
  tests.vendor module). Python 2.7 is still fully supported.
- Remodel CI:
  - on GitHub switched from Travis-CI to GH Actions
  - on GitLab-CI: stop testing 2.7 on Fedora, add centos7
  - update appveyor.yml
- Stop playing with swig in setup.py, we don't support swig 1.*
  anymore.
- Fix dereferencing of pointers (gl#m2crypto/m2crypto#281)
- Replace deprecated PyObject_AsReadBuffer with our own shim
  (thanks to Casey Deccio for saving my bacon there).
- Use parametrized to create parametrized tests (new external
  dependency).
- Only use DigestSign() and DigestUpdate() with OpenSSL >= 1.1.1
- Expose all the X509_V_FLAG
- Add support for DigestSign* and DigestVerify*