PR for building wheels and other improvements

[laggykiller]

I have created a fork: https://github.com/laggykiller/sqlcipher3

What is improved:

• Using conan to install openssl (dependency of sqlcipher)
• Building with sqlcipher version 4
• Building without scripts in build-scripts, reducing code to maintain
• Compatibility with openssl3
• Including amalgamation files (sqlite3.c and sqlite3.h) in sdist that is uploaded to pypi
• Workflow
  • Building wheels for Windows, MacOS and Linux with cibuildwheels. All architectures supported by cibuildwheel should be working (x86_64, i686, aarch64, ppc64le, s390x)
  • Test wheels and source distribution
  • Auto upload wheels to pypi (PYPI_API_TOKEN need to be added in repository secrets)
• Using the more modren pyproject.toml
  • Specifies build time requirements in pyproject.toml so that they don't have to be explicitly installed using pip before building
  • Note that name, version, package_dir and packages need not to be specified in setup.py if they are specified in pyproject.toml but they are kept or else python <= 3.6 wheel building would fail
• Rename python test scripts to test_*.py for running python -m unittest easily

Note that I referenced with this fork that improved on pysqlite3 (https://github.com/Dobatymo/pysqlite3). See if you also want to get a PR from there for pysqlite3.

Here is the diff: master...laggykiller:sqlcipher3:master

I have uploaded the wheels to pypi: https://pypi.org/project/sqlcipher3-wheels

If you are interested in PR, please tell me what improvements you want and don't want, then I will open a PR.

If you are not interested in PR, I can just maintain sqlcipher3-wheels