v0.4.0

Fixes

• Heatmaps look for existing colors in adata.uns by @codyheiser in #46
• Fixing the filter sizes by @redst4r in #51

Other changes

• Switch to cookiecutter-scverse template by @grst in #42. This implies
  • change of the build system to hatch
  • move documentation from github pages to readthedocs.