muse2 2.1.0

A tool for running simulations of energy systems
Documentation
# Description

*Please include a summary of the change and which issue is fixed (if any). Please also
include relevant motivation and context. List any dependencies that are required for
this change.*

Fixes # (issue)

## Type of change

- [ ] Bug fix (non-breaking change to fix an issue)
- [ ] New feature (non-breaking change to add functionality)
- [ ] Refactoring (non-breaking, non-functional change to improve maintainability)
- [ ] Optimization (non-breaking change to speed up the code)
- [ ] Breaking change (whatever its nature)
- [ ] Documentation (improve or add documentation)

## Key checklist

- [ ] All tests pass: `$ cargo test`
- [ ] The documentation builds and looks OK: `$ cargo doc`
- [ ] Update release notes for the latest release if this PR adds a new feature or fixes a bug
      present in the previous release

## Further checks

- [ ] Code is commented, particularly in hard-to-understand areas
- [ ] Tests added that prove fix is effective or that feature works