Scippnexus

Update to new documentation build process and update docs theme

Update to new documentation build process and update docs theme

Update to new documentation build process and update docs theme

What's Changed
* Avoid deprecation warnings in scipp dev builds and next release by SimonHeybrock in https://github.com/scipp/scippnexus/pull/37


**Full Changelog**: https://github.com/scipp/scippnexus/compare/0.1.3...0.1.4

What's Changed
* Fix slicing by SimonHeybrock in https://github.com/scipp/scippnexus/pull/36


**Full Changelog**: https://github.com/scipp/scippnexus/compare/0.1.2...0.1.3

What's Changed
* Only squeeze dimensions that are beyond the list of dims specified in Field by nvaytet in https://github.com/scipp/scippnexus/pull/32

New Contributors
* nvaytet made their first contribution in https://github.com/scipp/scippnexus/pull/32

**Full Changelog**: https://github.com/scipp/scippnexus/compare/0.1.1...0.1.2