v0.1.6

This release enhances several aspects of the spey workflow:

• Users will be able to access the gradient and hessian functions of the statistical models.
• Enhance the logging structure of the package, including debugging tools.
• Gradient execution has been optimised for faster optimisation.
• Spey will be able to provide BibTeX information for third-party plug-ins through their arXiv number, DOI and Zenodo identifiers (if provided in plug-in metadata).

What's Changed

• Logging and BibTeX by @jackaraz in #32
• Optimise gradient execution by @jackaraz in #31
• logging, gradients, and BibTeX by @jackaraz in #33

Full Changelog: v0.1.5...v0.1.6