sign Cython libraries

[EpigeneMax]

Description and Context

Closes #157

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• No code (non-breaking change that does not impact code: formatting, build system, documentation...)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Release (version number increment, possibly with documentation updates)