Cff2pages

* Added support for HTML and Markdown output.
* Implemented argument parsing for input file and output path.
* **Behavior change**: The default output file is now `public/citation.html`.
* Markdown output is not yet fully supported.
* Included a "Cite As" box in the HTML output.
* Fixed issue allowing authors without affiliations.
* Refactored templates to encapsulate all modules.
* Added docstrings; Sphinx documentation to be added in the future.

* convert references
* added tests for new conversion

* added Zenodo DOI to Citation.cff
* moved CSS-styles to its own file
* made generated html more readable
* added unit tests

* added version test
* added publish action
* rework README

* create first html-page based on cff attributes:
* title
* authors
* keywords
* identifiers
* licence
* abstract