Update to v1.2.1

[codecov[bot]]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (84d842e) 98.32% compared to head (879aa50) 97.93%. Report is 1 commits behind head on main.

Files	Patch %	Lines
src/twobody.jl	87.50%	16 Missing :warning:
src/transform.jl	92.30%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #46 +/- ## ========================================== - Coverage 98.32% 97.93% -0.40% ========================================== Files 22 26 +4 Lines 2030 2466 +436 ========================================== + Hits 1996 2415 +419 - Misses 34 51 +17 ```

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